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Python Runtime Services</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body"> <div class="section" id="module-inspect"> <span id="inspect-inspect-live-objects"></span><h1>28.12. <a class="reference internal" href="#module-inspect" title="inspect: Extract information and source code from live objects."><tt class="xref py py-mod docutils literal"><span class="pre">inspect</span></tt></a> — Inspect live objects<a class="headerlink" href="#module-inspect" title="Permalink to this headline">¶</a></h1> <p><strong>Source code:</strong> <a class="reference external" href="http://hg.python.org/cpython/file/3.3/Lib/inspect.py">Lib/inspect.py</a></p> <hr class="docutils" /> <p>The <a class="reference internal" href="#module-inspect" title="inspect: Extract information and source code from live objects."><tt class="xref py py-mod docutils literal"><span class="pre">inspect</span></tt></a> module provides several useful functions to help get information about live objects such as modules, classes, methods, functions, tracebacks, frame objects, and code objects. For example, it can help you examine the contents of a class, retrieve the source code of a method, extract and format the argument list for a function, or get all the information you need to display a detailed traceback.</p> <p>There are four main kinds of services provided by this module: type checking, getting source code, inspecting classes and functions, and examining the interpreter stack.</p> <div class="section" id="types-and-members"> <span id="inspect-types"></span><h2>28.12.1. Types and members<a class="headerlink" href="#types-and-members" title="Permalink to this headline">¶</a></h2> <p>The <a class="reference internal" href="#inspect.getmembers" title="inspect.getmembers"><tt class="xref py py-func docutils literal"><span class="pre">getmembers()</span></tt></a> function retrieves the members of an object such as a class or module. The sixteen functions whose names begin with “is” are mainly provided as convenient choices for the second argument to <a class="reference internal" href="#inspect.getmembers" title="inspect.getmembers"><tt class="xref py py-func docutils literal"><span class="pre">getmembers()</span></tt></a>. They also help you determine when you can expect to find the following special attributes:</p> <table border="1" class="docutils"> <colgroup> <col width="20%" /> <col width="31%" /> <col width="49%" /> </colgroup> <thead valign="bottom"> <tr><th class="head">Type</th> <th class="head">Attribute</th> <th class="head">Description</th> </tr> </thead> <tbody valign="top"> <tr><td>module</td> <td>__doc__</td> <td>documentation string</td> </tr> <tr><td> </td> <td>__file__</td> <td>filename (missing for built-in modules)</td> </tr> <tr><td>class</td> <td>__doc__</td> <td>documentation string</td> </tr> <tr><td> </td> <td>__module__</td> <td>name of module in which this class was defined</td> </tr> <tr><td>method</td> <td>__doc__</td> <td>documentation string</td> </tr> <tr><td> </td> <td>__name__</td> <td>name with which this method was defined</td> </tr> <tr><td> </td> <td>__func__</td> <td>function object containing implementation of method</td> </tr> <tr><td> </td> <td>__self__</td> <td>instance to which this method is bound, or <tt class="xref docutils literal"><span class="pre">None</span></tt></td> </tr> <tr><td>function</td> <td>__doc__</td> <td>documentation string</td> </tr> <tr><td> </td> <td>__name__</td> <td>name with which this function was defined</td> </tr> <tr><td> </td> <td>__code__</td> <td>code object containing compiled function <a class="reference internal" href="../glossary.html#term-bytecode"><em class="xref std std-term">bytecode</em></a></td> </tr> <tr><td> </td> <td>__defaults__</td> <td>tuple of any default values for arguments</td> </tr> <tr><td> </td> <td>__globals__</td> <td>global namespace in which this function was defined</td> </tr> <tr><td>traceback</td> <td>tb_frame</td> <td>frame object at this level</td> </tr> <tr><td> </td> <td>tb_lasti</td> <td>index of last attempted instruction in bytecode</td> </tr> <tr><td> </td> <td>tb_lineno</td> <td>current line number in Python source code</td> </tr> <tr><td> </td> <td>tb_next</td> <td>next inner traceback object (called by this level)</td> </tr> <tr><td>frame</td> <td>f_back</td> <td>next outer frame object (this frame’s caller)</td> </tr> <tr><td> </td> <td>f_builtins</td> <td>builtins namespace seen by this frame</td> </tr> <tr><td> </td> <td>f_code</td> <td>code object being executed in this frame</td> </tr> <tr><td> </td> <td>f_globals</td> <td>global namespace seen by this frame</td> </tr> <tr><td> </td> <td>f_lasti</td> <td>index of last attempted instruction in bytecode</td> </tr> <tr><td> </td> <td>f_lineno</td> <td>current line number in Python source code</td> </tr> <tr><td> </td> <td>f_locals</td> <td>local namespace seen by this frame</td> </tr> <tr><td> </td> <td>f_restricted</td> <td>0 or 1 if frame is in restricted execution mode</td> </tr> <tr><td> </td> <td>f_trace</td> <td>tracing function for this frame, or <tt class="xref docutils literal"><span class="pre">None</span></tt></td> </tr> <tr><td>code</td> <td>co_argcount</td> <td>number of arguments (not including * or ** args)</td> </tr> <tr><td> </td> <td>co_code</td> <td>string of raw compiled bytecode</td> </tr> <tr><td> </td> <td>co_consts</td> <td>tuple of constants used in the bytecode</td> </tr> <tr><td> </td> <td>co_filename</td> <td>name of file in which this code object was created</td> </tr> <tr><td> </td> <td>co_firstlineno</td> <td>number of first line in Python source code</td> </tr> <tr><td> </td> <td>co_flags</td> <td>bitmap: 1=optimized <tt class="docutils literal"><span class="pre">|</span></tt> 2=newlocals <tt class="docutils literal"><span class="pre">|</span></tt> 4=*arg <tt class="docutils literal"><span class="pre">|</span></tt> 8=**arg</td> </tr> <tr><td> </td> <td>co_lnotab</td> <td>encoded mapping of line numbers to bytecode indices</td> </tr> <tr><td> </td> <td>co_name</td> <td>name with which this code object was defined</td> </tr> <tr><td> </td> <td>co_names</td> <td>tuple of names of local variables</td> </tr> <tr><td> </td> <td>co_nlocals</td> <td>number of local variables</td> </tr> <tr><td> </td> <td>co_stacksize</td> <td>virtual machine stack space required</td> </tr> <tr><td> </td> <td>co_varnames</td> <td>tuple of names of arguments and local variables</td> </tr> <tr><td>builtin</td> <td>__doc__</td> <td>documentation string</td> </tr> <tr><td> </td> <td>__name__</td> <td>original name of this function or method</td> </tr> <tr><td> </td> <td>__self__</td> <td>instance to which a method is bound, or <tt class="xref docutils literal"><span class="pre">None</span></tt></td> </tr> </tbody> </table> <dl class="function"> <dt id="inspect.getmembers"> <tt class="descclassname">inspect.</tt><tt class="descname">getmembers</tt><big>(</big><em>object</em><span class="optional">[</span>, <em>predicate</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#inspect.getmembers" title="Permalink to this definition">¶</a></dt> <dd><p>Return all the members of an object in a list of (name, value) pairs sorted by name. If the optional <em>predicate</em> argument is supplied, only members for which the predicate returns a true value are included.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last"><a class="reference internal" href="#inspect.getmembers" title="inspect.getmembers"><tt class="xref py py-func docutils literal"><span class="pre">getmembers()</span></tt></a> does not return metaclass attributes when the argument is a class (this behavior is inherited from the <a class="reference internal" href="functions.html#dir" title="dir"><tt class="xref py py-func docutils literal"><span class="pre">dir()</span></tt></a> function).</p> </div> </dd></dl> <dl class="function"> <dt id="inspect.getmoduleinfo"> <tt class="descclassname">inspect.</tt><tt class="descname">getmoduleinfo</tt><big>(</big><em>path</em><big>)</big><a class="headerlink" href="#inspect.getmoduleinfo" title="Permalink to this definition">¶</a></dt> <dd><p>Returns a <a class="reference internal" href="../glossary.html#term-named-tuple"><em class="xref std std-term">named tuple</em></a> <tt class="docutils literal"><span class="pre">ModuleInfo(name,</span> <span class="pre">suffix,</span> <span class="pre">mode,</span> <span class="pre">module_type)</span></tt> of values that describe how Python will interpret the file identified by <em>path</em> if it is a module, or <tt class="xref docutils literal"><span class="pre">None</span></tt> if it would not be identified as a module. In that tuple, <em>name</em> is the name of the module without the name of any enclosing package, <em>suffix</em> is the trailing part of the file name (which may not be a dot-delimited extension), <em>mode</em> is the <a class="reference internal" href="functions.html#open" title="open"><tt class="xref py py-func docutils literal"><span class="pre">open()</span></tt></a> mode that would be used (<tt class="docutils literal"><span class="pre">'r'</span></tt> or <tt class="docutils literal"><span class="pre">'rb'</span></tt>), and <em>module_type</em> is an integer giving the type of the module. <em>module_type</em> will have a value which can be compared to the constants defined in the <a class="reference internal" href="imp.html#module-imp" title="imp: Access the implementation of the import statement."><tt class="xref py py-mod docutils literal"><span class="pre">imp</span></tt></a> module; see the documentation for that module for more information on module types.</p> <p class="deprecated"> <span class="versionmodified">Deprecated since version 3.3:</span> You may check the file path’s suffix against the supported suffixes listed in <a class="reference internal" href="importlib.html#module-importlib.machinery" title="importlib.machinery: Importers and path hooks"><tt class="xref py py-mod docutils literal"><span class="pre">importlib.machinery</span></tt></a> to infer the same information.</p> </dd></dl> <dl class="function"> <dt id="inspect.getmodulename"> <tt class="descclassname">inspect.</tt><tt class="descname">getmodulename</tt><big>(</big><em>path</em><big>)</big><a class="headerlink" href="#inspect.getmodulename" title="Permalink to this definition">¶</a></dt> <dd><p>Return the name of the module named by the file <em>path</em>, without including the names of enclosing packages. The file extension is checked against all of the entries in <a class="reference internal" href="importlib.html#importlib.machinery.all_suffixes" title="importlib.machinery.all_suffixes"><tt class="xref py py-func docutils literal"><span class="pre">importlib.machinery.all_suffixes()</span></tt></a>. If it matches, the final path component is returned with the extension removed. Otherwise, <tt class="xref docutils literal"><span class="pre">None</span></tt> is returned.</p> <p>Note that this function <em>only</em> returns a meaningful name for actual Python modules - paths that potentially refer to Python packages will still return <tt class="xref docutils literal"><span class="pre">None</span></tt>.</p> <p class="versionchanged"> <span class="versionmodified">Changed in version 3.3:</span> This function is now based directly on <a class="reference internal" href="importlib.html#module-importlib" title="importlib: An implementation of the import machinery."><tt class="xref py py-mod docutils literal"><span class="pre">importlib</span></tt></a> rather than the deprecated <a class="reference internal" href="#inspect.getmoduleinfo" title="inspect.getmoduleinfo"><tt class="xref py py-func docutils literal"><span class="pre">getmoduleinfo()</span></tt></a>.</p> </dd></dl> <dl class="function"> <dt id="inspect.ismodule"> <tt class="descclassname">inspect.</tt><tt class="descname">ismodule</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.ismodule" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a module.</p> </dd></dl> <dl class="function"> <dt id="inspect.isclass"> <tt class="descclassname">inspect.</tt><tt class="descname">isclass</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isclass" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a class, whether built-in or created in Python code.</p> </dd></dl> <dl class="function"> <dt id="inspect.ismethod"> <tt class="descclassname">inspect.</tt><tt class="descname">ismethod</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.ismethod" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a bound method written in Python.</p> </dd></dl> <dl class="function"> <dt id="inspect.isfunction"> <tt class="descclassname">inspect.</tt><tt class="descname">isfunction</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isfunction" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a Python function, which includes functions created by a <a class="reference internal" href="../glossary.html#term-lambda"><em class="xref std std-term">lambda</em></a> expression.</p> </dd></dl> <dl class="function"> <dt id="inspect.isgeneratorfunction"> <tt class="descclassname">inspect.</tt><tt class="descname">isgeneratorfunction</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isgeneratorfunction" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a Python generator function.</p> </dd></dl> <dl class="function"> <dt id="inspect.isgenerator"> <tt class="descclassname">inspect.</tt><tt class="descname">isgenerator</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isgenerator" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a generator.</p> </dd></dl> <dl class="function"> <dt id="inspect.istraceback"> <tt class="descclassname">inspect.</tt><tt class="descname">istraceback</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.istraceback" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a traceback.</p> </dd></dl> <dl class="function"> <dt id="inspect.isframe"> <tt class="descclassname">inspect.</tt><tt class="descname">isframe</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isframe" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a frame.</p> </dd></dl> <dl class="function"> <dt id="inspect.iscode"> <tt class="descclassname">inspect.</tt><tt class="descname">iscode</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.iscode" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a code.</p> </dd></dl> <dl class="function"> <dt id="inspect.isbuiltin"> <tt class="descclassname">inspect.</tt><tt class="descname">isbuiltin</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isbuiltin" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a built-in function or a bound built-in method.</p> </dd></dl> <dl class="function"> <dt id="inspect.isroutine"> <tt class="descclassname">inspect.</tt><tt class="descname">isroutine</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isroutine" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a user-defined or built-in function or method.</p> </dd></dl> <dl class="function"> <dt id="inspect.isabstract"> <tt class="descclassname">inspect.</tt><tt class="descname">isabstract</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isabstract" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is an abstract base class.</p> </dd></dl> <dl class="function"> <dt id="inspect.ismethoddescriptor"> <tt class="descclassname">inspect.</tt><tt class="descname">ismethoddescriptor</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.ismethoddescriptor" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a method descriptor, but not if <a class="reference internal" href="#inspect.ismethod" title="inspect.ismethod"><tt class="xref py py-func docutils literal"><span class="pre">ismethod()</span></tt></a>, <a class="reference internal" href="#inspect.isclass" title="inspect.isclass"><tt class="xref py py-func docutils literal"><span class="pre">isclass()</span></tt></a>, <a class="reference internal" href="#inspect.isfunction" title="inspect.isfunction"><tt class="xref py py-func docutils literal"><span class="pre">isfunction()</span></tt></a> or <a class="reference internal" href="#inspect.isbuiltin" title="inspect.isbuiltin"><tt class="xref py py-func docutils literal"><span class="pre">isbuiltin()</span></tt></a> are true.</p> <p>This, for example, is true of <tt class="docutils literal"><span class="pre">int.__add__</span></tt>. An object passing this test has a <tt class="xref py py-attr docutils literal"><span class="pre">__get__</span></tt> attribute but not a <tt class="xref py py-attr docutils literal"><span class="pre">__set__</span></tt> attribute, but beyond that the set of attributes varies. <tt class="xref py py-attr docutils literal"><span class="pre">__name__</span></tt> is usually sensible, and <tt class="xref py py-attr docutils literal"><span class="pre">__doc__</span></tt> often is.</p> <p>Methods implemented via descriptors that also pass one of the other tests return false from the <a class="reference internal" href="#inspect.ismethoddescriptor" title="inspect.ismethoddescriptor"><tt class="xref py py-func docutils literal"><span class="pre">ismethoddescriptor()</span></tt></a> test, simply because the other tests promise more – you can, e.g., count on having the <tt class="xref py py-attr docutils literal"><span class="pre">__func__</span></tt> attribute (etc) when an object passes <a class="reference internal" href="#inspect.ismethod" title="inspect.ismethod"><tt class="xref py py-func docutils literal"><span class="pre">ismethod()</span></tt></a>.</p> </dd></dl> <dl class="function"> <dt id="inspect.isdatadescriptor"> <tt class="descclassname">inspect.</tt><tt class="descname">isdatadescriptor</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isdatadescriptor" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a data descriptor.</p> <p>Data descriptors have both a <tt class="xref py py-attr docutils literal"><span class="pre">__get__</span></tt> and a <tt class="xref py py-attr docutils literal"><span class="pre">__set__</span></tt> attribute. Examples are properties (defined in Python), getsets, and members. The latter two are defined in C and there are more specific tests available for those types, which is robust across Python implementations. Typically, data descriptors will also have <tt class="xref py py-attr docutils literal"><span class="pre">__name__</span></tt> and <tt class="xref py py-attr docutils literal"><span class="pre">__doc__</span></tt> attributes (properties, getsets, and members have both of these attributes), but this is not guaranteed.</p> </dd></dl> <dl class="function"> <dt id="inspect.isgetsetdescriptor"> <tt class="descclassname">inspect.</tt><tt class="descname">isgetsetdescriptor</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.isgetsetdescriptor" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a getset descriptor.</p> <div class="impl-detail compound"> <p><strong>CPython implementation detail:</strong> getsets are attributes defined in extension modules via <tt class="xref c c-type docutils literal"><span class="pre">PyGetSetDef</span></tt> structures. For Python implementations without such types, this method will always return <tt class="xref docutils literal"><span class="pre">False</span></tt>.</p> </div> </dd></dl> <dl class="function"> <dt id="inspect.ismemberdescriptor"> <tt class="descclassname">inspect.</tt><tt class="descname">ismemberdescriptor</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.ismemberdescriptor" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the object is a member descriptor.</p> <div class="impl-detail compound"> <p><strong>CPython implementation detail:</strong> Member descriptors are attributes defined in extension modules via <a class="reference internal" href="../c-api/structures.html#PyMemberDef" title="PyMemberDef"><tt class="xref c c-type docutils literal"><span class="pre">PyMemberDef</span></tt></a> structures. For Python implementations without such types, this method will always return <tt class="xref docutils literal"><span class="pre">False</span></tt>.</p> </div> </dd></dl> </div> <div class="section" id="retrieving-source-code"> <span id="inspect-source"></span><h2>28.12.2. Retrieving source code<a class="headerlink" href="#retrieving-source-code" title="Permalink to this headline">¶</a></h2> <dl class="function"> <dt id="inspect.getdoc"> <tt class="descclassname">inspect.</tt><tt class="descname">getdoc</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.getdoc" title="Permalink to this definition">¶</a></dt> <dd><p>Get the documentation string for an object, cleaned up with <a class="reference internal" href="#inspect.cleandoc" title="inspect.cleandoc"><tt class="xref py py-func docutils literal"><span class="pre">cleandoc()</span></tt></a>.</p> </dd></dl> <dl class="function"> <dt id="inspect.getcomments"> <tt class="descclassname">inspect.</tt><tt class="descname">getcomments</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.getcomments" title="Permalink to this definition">¶</a></dt> <dd><p>Return in a single string any lines of comments immediately preceding the object’s source code (for a class, function, or method), or at the top of the Python source file (if the object is a module).</p> </dd></dl> <dl class="function"> <dt id="inspect.getfile"> <tt class="descclassname">inspect.</tt><tt class="descname">getfile</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.getfile" title="Permalink to this definition">¶</a></dt> <dd><p>Return the name of the (text or binary) file in which an object was defined. This will fail with a <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><tt class="xref py py-exc docutils literal"><span class="pre">TypeError</span></tt></a> if the object is a built-in module, class, or function.</p> </dd></dl> <dl class="function"> <dt id="inspect.getmodule"> <tt class="descclassname">inspect.</tt><tt class="descname">getmodule</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.getmodule" title="Permalink to this definition">¶</a></dt> <dd><p>Try to guess which module an object was defined in.</p> </dd></dl> <dl class="function"> <dt id="inspect.getsourcefile"> <tt class="descclassname">inspect.</tt><tt class="descname">getsourcefile</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.getsourcefile" title="Permalink to this definition">¶</a></dt> <dd><p>Return the name of the Python source file in which an object was defined. This will fail with a <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><tt class="xref py py-exc docutils literal"><span class="pre">TypeError</span></tt></a> if the object is a built-in module, class, or function.</p> </dd></dl> <dl class="function"> <dt id="inspect.getsourcelines"> <tt class="descclassname">inspect.</tt><tt class="descname">getsourcelines</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.getsourcelines" title="Permalink to this definition">¶</a></dt> <dd><p>Return a list of source lines and starting line number for an object. The argument may be a module, class, method, function, traceback, frame, or code object. The source code is returned as a list of the lines corresponding to the object and the line number indicates where in the original source file the first line of code was found. An <a class="reference internal" href="exceptions.html#OSError" title="OSError"><tt class="xref py py-exc docutils literal"><span class="pre">OSError</span></tt></a> is raised if the source code cannot be retrieved.</p> <p class="versionchanged"> <span class="versionmodified">Changed in version 3.3:</span> <a class="reference internal" href="exceptions.html#OSError" title="OSError"><tt class="xref py py-exc docutils literal"><span class="pre">OSError</span></tt></a> is raised instead of <a class="reference internal" href="exceptions.html#IOError" title="IOError"><tt class="xref py py-exc docutils literal"><span class="pre">IOError</span></tt></a>, now an alias of the former.</p> </dd></dl> <dl class="function"> <dt id="inspect.getsource"> <tt class="descclassname">inspect.</tt><tt class="descname">getsource</tt><big>(</big><em>object</em><big>)</big><a class="headerlink" href="#inspect.getsource" title="Permalink to this definition">¶</a></dt> <dd><p>Return the text of the source code for an object. The argument may be a module, class, method, function, traceback, frame, or code object. The source code is returned as a single string. An <a class="reference internal" href="exceptions.html#OSError" title="OSError"><tt class="xref py py-exc docutils literal"><span class="pre">OSError</span></tt></a> is raised if the source code cannot be retrieved.</p> <p class="versionchanged"> <span class="versionmodified">Changed in version 3.3:</span> <a class="reference internal" href="exceptions.html#OSError" title="OSError"><tt class="xref py py-exc docutils literal"><span class="pre">OSError</span></tt></a> is raised instead of <a class="reference internal" href="exceptions.html#IOError" title="IOError"><tt class="xref py py-exc docutils literal"><span class="pre">IOError</span></tt></a>, now an alias of the former.</p> </dd></dl> <dl class="function"> <dt id="inspect.cleandoc"> <tt class="descclassname">inspect.</tt><tt class="descname">cleandoc</tt><big>(</big><em>doc</em><big>)</big><a class="headerlink" href="#inspect.cleandoc" title="Permalink to this definition">¶</a></dt> <dd><p>Clean up indentation from docstrings that are indented to line up with blocks of code. Any whitespace that can be uniformly removed from the second line onwards is removed. Also, all tabs are expanded to spaces.</p> </dd></dl> </div> <div class="section" id="introspecting-callables-with-the-signature-object"> <span id="inspect-signature-object"></span><h2>28.12.3. Introspecting callables with the Signature object<a class="headerlink" href="#introspecting-callables-with-the-signature-object" title="Permalink to this headline">¶</a></h2> <p class="versionadded"> <span class="versionmodified">New in version 3.3.</span> </p> <p>The Signature object represents the call signature of a callable object and its return annotation. To retrieve a Signature object, use the <a class="reference internal" href="#inspect.signature" title="inspect.signature"><tt class="xref py py-func docutils literal"><span class="pre">signature()</span></tt></a> function.</p> <dl class="function"> <dt id="inspect.signature"> <tt class="descclassname">inspect.</tt><tt class="descname">signature</tt><big>(</big><em>callable</em><big>)</big><a class="headerlink" href="#inspect.signature" title="Permalink to this definition">¶</a></dt> <dd><p>Return a <a class="reference internal" href="#inspect.Signature" title="inspect.Signature"><tt class="xref py py-class docutils literal"><span class="pre">Signature</span></tt></a> object for the given <tt class="docutils literal"><span class="pre">callable</span></tt>:</p> <div class="highlight-python3"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">inspect</span> <span class="k">import</span> <span class="n">signature</span> <span class="gp">>>> </span><span class="k">def</span> <span class="nf">foo</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="o">*</span><span class="p">,</span> <span class="n">b</span><span class="p">:</span><span class="nb">int</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span> <span class="gp">... </span> <span class="k">pass</span> <span class="gp">>>> </span><span class="n">sig</span> <span class="o">=</span> <span class="n">signature</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span> <span class="gp">>>> </span><span class="nb">str</span><span class="p">(</span><span class="n">sig</span><span class="p">)</span> <span class="go">'(a, *, b:int, **kwargs)'</span> <span class="gp">>>> </span><span class="nb">str</span><span class="p">(</span><span class="n">sig</span><span class="o">.</span><span class="n">parameters</span><span class="p">[</span><span class="s">'b'</span><span class="p">])</span> <span class="go">'b:int'</span> <span class="gp">>>> </span><span class="n">sig</span><span class="o">.</span><span class="n">parameters</span><span class="p">[</span><span class="s">'b'</span><span class="p">]</span><span class="o">.</span><span class="n">annotation</span> <span class="go"><class 'int'></span> </pre></div> </div> <p>Accepts a wide range of python callables, from plain functions and classes to <a class="reference internal" href="functools.html#functools.partial" title="functools.partial"><tt class="xref py py-func docutils literal"><span class="pre">functools.partial()</span></tt></a> objects.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">Some callables may not be introspectable in certain implementations of Python. For example, in CPython, built-in functions defined in C provide no metadata about their arguments.</p> </div> </dd></dl> <dl class="class"> <dt id="inspect.Signature"> <em class="property">class </em><tt class="descclassname">inspect.</tt><tt class="descname">Signature</tt><a class="headerlink" href="#inspect.Signature" title="Permalink to this definition">¶</a></dt> <dd><p>A Signature object represents the call signature of a function and its return annotation. For each parameter accepted by the function it stores a <a class="reference internal" href="#inspect.Parameter" title="inspect.Parameter"><tt class="xref py py-class docutils literal"><span class="pre">Parameter</span></tt></a> object in its <a class="reference internal" href="#inspect.Signature.parameters" title="inspect.Signature.parameters"><tt class="xref py py-attr docutils literal"><span class="pre">parameters</span></tt></a> collection.</p> <p>Signature objects are <em>immutable</em>. Use <a class="reference internal" href="#inspect.Signature.replace" title="inspect.Signature.replace"><tt class="xref py py-meth docutils literal"><span class="pre">Signature.replace()</span></tt></a> to make a modified copy.</p> <dl class="attribute"> <dt id="inspect.Signature.empty"> <tt class="descname">empty</tt><a class="headerlink" href="#inspect.Signature.empty" title="Permalink to this definition">¶</a></dt> <dd><p>A special class-level marker to specify absence of a return annotation.</p> </dd></dl> <dl class="attribute"> <dt id="inspect.Signature.parameters"> <tt class="descname">parameters</tt><a class="headerlink" href="#inspect.Signature.parameters" title="Permalink to this definition">¶</a></dt> <dd><p>An ordered mapping of parameters’ names to the corresponding <a class="reference internal" href="#inspect.Parameter" title="inspect.Parameter"><tt class="xref py py-class docutils literal"><span class="pre">Parameter</span></tt></a> objects.</p> </dd></dl> <dl class="attribute"> <dt id="inspect.Signature.return_annotation"> <tt class="descname">return_annotation</tt><a class="headerlink" href="#inspect.Signature.return_annotation" title="Permalink to this definition">¶</a></dt> <dd><p>The “return” annotation for the callable. If the callable has no “return” annotation, this attribute is set to <a class="reference internal" href="#inspect.Signature.empty" title="inspect.Signature.empty"><tt class="xref py py-attr docutils literal"><span class="pre">Signature.empty</span></tt></a>.</p> </dd></dl> <dl class="method"> <dt id="inspect.Signature.bind"> <tt class="descname">bind</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#inspect.Signature.bind" title="Permalink to this definition">¶</a></dt> <dd><p>Create a mapping from positional and keyword arguments to parameters. Returns <a class="reference internal" href="#inspect.BoundArguments" title="inspect.BoundArguments"><tt class="xref py py-class docutils literal"><span class="pre">BoundArguments</span></tt></a> if <tt class="docutils literal"><span class="pre">*args</span></tt> and <tt class="docutils literal"><span class="pre">**kwargs</span></tt> match the signature, or raises a <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><tt class="xref py py-exc docutils literal"><span class="pre">TypeError</span></tt></a>.</p> </dd></dl> <dl class="method"> <dt id="inspect.Signature.bind_partial"> <tt class="descname">bind_partial</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="headerlink" href="#inspect.Signature.bind_partial" title="Permalink to this definition">¶</a></dt> <dd><p>Works the same way as <a class="reference internal" href="#inspect.Signature.bind" title="inspect.Signature.bind"><tt class="xref py py-meth docutils literal"><span class="pre">Signature.bind()</span></tt></a>, but allows the omission of some required arguments (mimics <a class="reference internal" href="functools.html#functools.partial" title="functools.partial"><tt class="xref py py-func docutils literal"><span class="pre">functools.partial()</span></tt></a> behavior.) Returns <a class="reference internal" href="#inspect.BoundArguments" title="inspect.BoundArguments"><tt class="xref py py-class docutils literal"><span class="pre">BoundArguments</span></tt></a>, or raises a <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><tt class="xref py py-exc docutils literal"><span class="pre">TypeError</span></tt></a> if the passed arguments do not match the signature.</p> </dd></dl> <dl class="method"> <dt id="inspect.Signature.replace"> <tt class="descname">replace</tt><big>(</big><em>*[, parameters][, return_annotation]</em><big>)</big><a class="headerlink" href="#inspect.Signature.replace" title="Permalink to this definition">¶</a></dt> <dd><p>Create a new Signature instance based on the instance replace was invoked on. It is possible to pass different <tt class="docutils literal"><span class="pre">parameters</span></tt> and/or <tt class="docutils literal"><span class="pre">return_annotation</span></tt> to override the corresponding properties of the base signature. To remove return_annotation from the copied Signature, pass in <a class="reference internal" href="#inspect.Signature.empty" title="inspect.Signature.empty"><tt class="xref py py-attr docutils literal"><span class="pre">Signature.empty</span></tt></a>.</p> <div class="highlight-python3"><div class="highlight"><pre><span class="gp">>>> </span><span class="k">def</span> <span class="nf">test</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="p">):</span> <span class="gp">... </span> <span class="k">pass</span> <span class="gp">>>> </span><span class="n">sig</span> <span class="o">=</span> <span class="n">signature</span><span class="p">(</span><span class="n">test</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">new_sig</span> <span class="o">=</span> <span class="n">sig</span><span class="o">.</span><span class="n">replace</span><span class="p">(</span><span class="n">return_annotation</span><span class="o">=</span><span class="s">"new return anno"</span><span class="p">)</span> <span class="gp">>>> </span><span class="nb">str</span><span class="p">(</span><span class="n">new_sig</span><span class="p">)</span> <span class="go">"(a, b) -> 'new return anno'"</span> </pre></div> </div> </dd></dl> </dd></dl> <dl class="class"> <dt id="inspect.Parameter"> <em class="property">class </em><tt class="descclassname">inspect.</tt><tt class="descname">Parameter</tt><a class="headerlink" href="#inspect.Parameter" title="Permalink to this definition">¶</a></dt> <dd><p>Parameter objects are <em>immutable</em>. Instead of modifying a Parameter object, you can use <a class="reference internal" href="#inspect.Parameter.replace" title="inspect.Parameter.replace"><tt class="xref py py-meth docutils literal"><span class="pre">Parameter.replace()</span></tt></a> to create a modified copy.</p> <dl class="attribute"> <dt id="inspect.Parameter.empty"> <tt class="descname">empty</tt><a class="headerlink" href="#inspect.Parameter.empty" title="Permalink to this definition">¶</a></dt> <dd><p>A special class-level marker to specify absence of default values and annotations.</p> </dd></dl> <dl class="attribute"> <dt id="inspect.Parameter.name"> <tt class="descname">name</tt><a class="headerlink" href="#inspect.Parameter.name" title="Permalink to this definition">¶</a></dt> <dd><p>The name of the parameter as a string. Must be a valid python identifier name (with the exception of <tt class="docutils literal"><span class="pre">POSITIONAL_ONLY</span></tt> parameters, which can have it set to <tt class="xref docutils literal"><span class="pre">None</span></tt>).</p> </dd></dl> <dl class="attribute"> <dt id="inspect.Parameter.default"> <tt class="descname">default</tt><a class="headerlink" href="#inspect.Parameter.default" title="Permalink to this definition">¶</a></dt> <dd><p>The default value for the parameter. If the parameter has no default value, this attribute is set to <a class="reference internal" href="#inspect.Parameter.empty" title="inspect.Parameter.empty"><tt class="xref py py-attr docutils literal"><span class="pre">Parameter.empty</span></tt></a>.</p> </dd></dl> <dl class="attribute"> <dt id="inspect.Parameter.annotation"> <tt class="descname">annotation</tt><a class="headerlink" href="#inspect.Parameter.annotation" title="Permalink to this definition">¶</a></dt> <dd><p>The annotation for the parameter. If the parameter has no annotation, this attribute is set to <a class="reference internal" href="#inspect.Parameter.empty" title="inspect.Parameter.empty"><tt class="xref py py-attr docutils literal"><span class="pre">Parameter.empty</span></tt></a>.</p> </dd></dl> <dl class="attribute"> <dt id="inspect.Parameter.kind"> <tt class="descname">kind</tt><a class="headerlink" href="#inspect.Parameter.kind" title="Permalink to this definition">¶</a></dt> <dd><p>Describes how argument values are bound to the parameter. Possible values (accessible via <a class="reference internal" href="#inspect.Parameter" title="inspect.Parameter"><tt class="xref py py-class docutils literal"><span class="pre">Parameter</span></tt></a>, like <tt class="docutils literal"><span class="pre">Parameter.KEYWORD_ONLY</span></tt>):</p> <table border="1" class="docutils"> <colgroup> <col width="34%" /> <col width="66%" /> </colgroup> <thead valign="bottom"> <tr><th class="head">Name</th> <th class="head">Meaning</th> </tr> </thead> <tbody valign="top"> <tr><td><em>POSITIONAL_ONLY</em></td> <td><p class="first">Value must be supplied as a positional argument.</p> <p class="last">Python has no explicit syntax for defining positional-only parameters, but many built-in and extension module functions (especially those that accept only one or two parameters) accept them.</p> </td> </tr> <tr><td><em>POSITIONAL_OR_KEYWORD</em></td> <td>Value may be supplied as either a keyword or positional argument (this is the standard binding behaviour for functions implemented in Python.)</td> </tr> <tr><td><em>VAR_POSITIONAL</em></td> <td>A tuple of positional arguments that aren’t bound to any other parameter. This corresponds to a <tt class="docutils literal"><span class="pre">*args</span></tt> parameter in a Python function definition.</td> </tr> <tr><td><em>KEYWORD_ONLY</em></td> <td>Value must be supplied as a keyword argument. Keyword only parameters are those which appear after a <tt class="docutils literal"><span class="pre">*</span></tt> or <tt class="docutils literal"><span class="pre">*args</span></tt> entry in a Python function definition.</td> </tr> <tr><td><em>VAR_KEYWORD</em></td> <td>A dict of keyword arguments that aren’t bound to any other parameter. This corresponds to a <tt class="docutils literal"><span class="pre">**kwargs</span></tt> parameter in a Python function definition.</td> </tr> </tbody> </table> <p>Example: print all keyword-only arguments without default values:</p> <div class="highlight-python3"><div class="highlight"><pre><span class="gp">>>> </span><span class="k">def</span> <span class="nf">foo</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="p">,</span> <span class="o">*</span><span class="p">,</span> <span class="n">c</span><span class="p">,</span> <span class="n">d</span><span class="o">=</span><span class="mi">10</span><span class="p">):</span> <span class="gp">... </span> <span class="k">pass</span> <span class="gp">>>> </span><span class="n">sig</span> <span class="o">=</span> <span class="n">signature</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span> <span class="gp">>>> </span><span class="k">for</span> <span class="n">param</span> <span class="ow">in</span> <span class="n">sig</span><span class="o">.</span><span class="n">parameters</span><span class="o">.</span><span class="n">values</span><span class="p">():</span> <span class="gp">... </span> <span class="k">if</span> <span class="p">(</span><span class="n">param</span><span class="o">.</span><span class="n">kind</span> <span class="o">==</span> <span class="n">param</span><span class="o">.</span><span class="n">KEYWORD_ONLY</span> <span class="ow">and</span> <span class="gp">... </span> <span class="n">param</span><span class="o">.</span><span class="n">default</span> <span class="ow">is</span> <span class="n">param</span><span class="o">.</span><span class="n">empty</span><span class="p">):</span> <span class="gp">... </span> <span class="nb">print</span><span class="p">(</span><span class="s">'Parameter:'</span><span class="p">,</span> <span class="n">param</span><span class="p">)</span> <span class="go">Parameter: c</span> </pre></div> </div> </dd></dl> <dl class="method"> <dt id="inspect.Parameter.replace"> <tt class="descname">replace</tt><big>(</big><em>*[, name][, kind][, default][, annotation]</em><big>)</big><a class="headerlink" href="#inspect.Parameter.replace" title="Permalink to this definition">¶</a></dt> <dd><p>Create a new Parameter instance based on the instance replaced was invoked on. To override a <a class="reference internal" href="#inspect.Parameter" title="inspect.Parameter"><tt class="xref py py-class docutils literal"><span class="pre">Parameter</span></tt></a> attribute, pass the corresponding argument. To remove a default value or/and an annotation from a Parameter, pass <a class="reference internal" href="#inspect.Parameter.empty" title="inspect.Parameter.empty"><tt class="xref py py-attr docutils literal"><span class="pre">Parameter.empty</span></tt></a>.</p> <div class="highlight-python3"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">inspect</span> <span class="k">import</span> <span class="n">Parameter</span> <span class="gp">>>> </span><span class="n">param</span> <span class="o">=</span> <span class="n">Parameter</span><span class="p">(</span><span class="s">'foo'</span><span class="p">,</span> <span class="n">Parameter</span><span class="o">.</span><span class="n">KEYWORD_ONLY</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="mi">42</span><span class="p">)</span> <span class="gp">>>> </span><span class="nb">str</span><span class="p">(</span><span class="n">param</span><span class="p">)</span> <span class="go">'foo=42'</span> <span class="gp">>>> </span><span class="nb">str</span><span class="p">(</span><span class="n">param</span><span class="o">.</span><span class="n">replace</span><span class="p">())</span> <span class="c"># Will create a shallow copy of 'param'</span> <span class="go">'foo=42'</span> <span class="gp">>>> </span><span class="nb">str</span><span class="p">(</span><span class="n">param</span><span class="o">.</span><span class="n">replace</span><span class="p">(</span><span class="n">default</span><span class="o">=</span><span class="n">Parameter</span><span class="o">.</span><span class="n">empty</span><span class="p">,</span> <span class="n">annotation</span><span class="o">=</span><span class="s">'spam'</span><span class="p">))</span> <span class="go">"foo:'spam'"</span> </pre></div> </div> </dd></dl> </dd></dl> <dl class="class"> <dt id="inspect.BoundArguments"> <em class="property">class </em><tt class="descclassname">inspect.</tt><tt class="descname">BoundArguments</tt><a class="headerlink" href="#inspect.BoundArguments" title="Permalink to this definition">¶</a></dt> <dd><p>Result of a <a class="reference internal" href="#inspect.Signature.bind" title="inspect.Signature.bind"><tt class="xref py py-meth docutils literal"><span class="pre">Signature.bind()</span></tt></a> or <a class="reference internal" href="#inspect.Signature.bind_partial" title="inspect.Signature.bind_partial"><tt class="xref py py-meth docutils literal"><span class="pre">Signature.bind_partial()</span></tt></a> call. Holds the mapping of arguments to the function’s parameters.</p> <dl class="attribute"> <dt id="inspect.BoundArguments.arguments"> <tt class="descname">arguments</tt><a class="headerlink" href="#inspect.BoundArguments.arguments" title="Permalink to this definition">¶</a></dt> <dd><p>An ordered, mutable mapping (<a class="reference internal" href="collections.html#collections.OrderedDict" title="collections.OrderedDict"><tt class="xref py py-class docutils literal"><span class="pre">collections.OrderedDict</span></tt></a>) of parameters’ names to arguments’ values. Contains only explicitly bound arguments. Changes in <a class="reference internal" href="#inspect.BoundArguments.arguments" title="inspect.BoundArguments.arguments"><tt class="xref py py-attr docutils literal"><span class="pre">arguments</span></tt></a> will reflect in <a class="reference internal" href="#inspect.BoundArguments.args" title="inspect.BoundArguments.args"><tt class="xref py py-attr docutils literal"><span class="pre">args</span></tt></a> and <a class="reference internal" href="#inspect.BoundArguments.kwargs" title="inspect.BoundArguments.kwargs"><tt class="xref py py-attr docutils literal"><span class="pre">kwargs</span></tt></a>.</p> <p>Should be used in conjunction with <a class="reference internal" href="#inspect.Signature.parameters" title="inspect.Signature.parameters"><tt class="xref py py-attr docutils literal"><span class="pre">Signature.parameters</span></tt></a> for any argument processing purposes.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">Arguments for which <a class="reference internal" href="#inspect.Signature.bind" title="inspect.Signature.bind"><tt class="xref py py-meth docutils literal"><span class="pre">Signature.bind()</span></tt></a> or <a class="reference internal" href="#inspect.Signature.bind_partial" title="inspect.Signature.bind_partial"><tt class="xref py py-meth docutils literal"><span class="pre">Signature.bind_partial()</span></tt></a> relied on a default value are skipped. However, if needed, it is easy to include them.</p> </div> <div class="highlight-python3"><div class="highlight"><pre><span class="gp">>>> </span><span class="k">def</span> <span class="nf">foo</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="o">=</span><span class="mi">10</span><span class="p">):</span> <span class="gp">... </span> <span class="k">pass</span> <span class="gp">>>> </span><span class="n">sig</span> <span class="o">=</span> <span class="n">signature</span><span class="p">(</span><span class="n">foo</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">ba</span> <span class="o">=</span> <span class="n">sig</span><span class="o">.</span><span class="n">bind</span><span class="p">(</span><span class="mi">5</span><span class="p">)</span> <span class="gp">>>> </span><span class="n">ba</span><span class="o">.</span><span class="n">args</span><span class="p">,</span> <span class="n">ba</span><span class="o">.</span><span class="n">kwargs</span> <span class="go">((5,), {})</span> <span class="gp">>>> </span><span class="k">for</span> <span class="n">param</span> <span class="ow">in</span> <span class="n">sig</span><span class="o">.</span><span class="n">parameters</span><span class="o">.</span><span class="n">values</span><span class="p">():</span> <span class="gp">... </span> <span class="k">if</span> <span class="n">param</span><span class="o">.</span><span class="n">name</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">ba</span><span class="o">.</span><span class="n">arguments</span><span class="p">:</span> <span class="gp">... </span> <span class="n">ba</span><span class="o">.</span><span class="n">arguments</span><span class="p">[</span><span class="n">param</span><span class="o">.</span><span class="n">name</span><span class="p">]</span> <span class="o">=</span> <span class="n">param</span><span class="o">.</span><span class="n">default</span> <span class="gp">>>> </span><span class="n">ba</span><span class="o">.</span><span class="n">args</span><span class="p">,</span> <span class="n">ba</span><span class="o">.</span><span class="n">kwargs</span> <span class="go">((5, 10), {})</span> </pre></div> </div> </dd></dl> <dl class="attribute"> <dt id="inspect.BoundArguments.args"> <tt class="descname">args</tt><a class="headerlink" href="#inspect.BoundArguments.args" title="Permalink to this definition">¶</a></dt> <dd><p>A tuple of positional arguments values. Dynamically computed from the <a class="reference internal" href="#inspect.BoundArguments.arguments" title="inspect.BoundArguments.arguments"><tt class="xref py py-attr docutils literal"><span class="pre">arguments</span></tt></a> attribute.</p> </dd></dl> <dl class="attribute"> <dt id="inspect.BoundArguments.kwargs"> <tt class="descname">kwargs</tt><a class="headerlink" href="#inspect.BoundArguments.kwargs" title="Permalink to this definition">¶</a></dt> <dd><p>A dict of keyword arguments values. Dynamically computed from the <a class="reference internal" href="#inspect.BoundArguments.arguments" title="inspect.BoundArguments.arguments"><tt class="xref py py-attr docutils literal"><span class="pre">arguments</span></tt></a> attribute.</p> </dd></dl> <p>The <a class="reference internal" href="#inspect.BoundArguments.args" title="inspect.BoundArguments.args"><tt class="xref py py-attr docutils literal"><span class="pre">args</span></tt></a> and <a class="reference internal" href="#inspect.BoundArguments.kwargs" title="inspect.BoundArguments.kwargs"><tt class="xref py py-attr docutils literal"><span class="pre">kwargs</span></tt></a> properties can be used to invoke functions:</p> <div class="highlight-python3"><div class="highlight"><pre><span class="k">def</span> <span class="nf">test</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="o">*</span><span class="p">,</span> <span class="n">b</span><span class="p">):</span> <span class="o">...</span> <span class="n">sig</span> <span class="o">=</span> <span class="n">signature</span><span class="p">(</span><span class="n">test</span><span class="p">)</span> <span class="n">ba</span> <span class="o">=</span> <span class="n">sig</span><span class="o">.</span><span class="n">bind</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span> <span class="n">b</span><span class="o">=</span><span class="mi">20</span><span class="p">)</span> <span class="n">test</span><span class="p">(</span><span class="o">*</span><span class="n">ba</span><span class="o">.</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">ba</span><span class="o">.</span><span class="n">kwargs</span><span class="p">)</span> </pre></div> </div> </dd></dl> <div class="admonition-see-also admonition seealso"> <p class="first admonition-title">See also</p> <dl class="last docutils"> <dt><span class="target" id="index-0"></span><a class="pep reference external" href="http://www.python.org/dev/peps/pep-0362"><strong>PEP 362</strong></a> - Function Signature Object.</dt> <dd>The detailed specification, implementation details and examples.</dd> </dl> </div> </div> <div class="section" id="classes-and-functions"> <span id="inspect-classes-functions"></span><h2>28.12.4. Classes and functions<a class="headerlink" href="#classes-and-functions" title="Permalink to this headline">¶</a></h2> <dl class="function"> <dt id="inspect.getclasstree"> <tt class="descclassname">inspect.</tt><tt class="descname">getclasstree</tt><big>(</big><em>classes</em>, <em>unique=False</em><big>)</big><a class="headerlink" href="#inspect.getclasstree" title="Permalink to this definition">¶</a></dt> <dd><p>Arrange the given list of classes into a hierarchy of nested lists. Where a nested list appears, it contains classes derived from the class whose entry immediately precedes the list. Each entry is a 2-tuple containing a class and a tuple of its base classes. If the <em>unique</em> argument is true, exactly one entry appears in the returned structure for each class in the given list. Otherwise, classes using multiple inheritance and their descendants will appear multiple times.</p> </dd></dl> <dl class="function"> <dt id="inspect.getargspec"> <tt class="descclassname">inspect.</tt><tt class="descname">getargspec</tt><big>(</big><em>func</em><big>)</big><a class="headerlink" href="#inspect.getargspec" title="Permalink to this definition">¶</a></dt> <dd><p>Get the names and default values of a Python function’s arguments. A <a class="reference internal" href="../glossary.html#term-named-tuple"><em class="xref std std-term">named tuple</em></a> <tt class="docutils literal"><span class="pre">ArgSpec(args,</span> <span class="pre">varargs,</span> <span class="pre">keywords,</span> <span class="pre">defaults)</span></tt> is returned. <em>args</em> is a list of the argument names. <em>varargs</em> and <em>keywords</em> are the names of the <tt class="docutils literal"><span class="pre">*</span></tt> and <tt class="docutils literal"><span class="pre">**</span></tt> arguments or <tt class="xref docutils literal"><span class="pre">None</span></tt>. <em>defaults</em> is a tuple of default argument values or <tt class="xref docutils literal"><span class="pre">None</span></tt> if there are no default arguments; if this tuple has <em>n</em> elements, they correspond to the last <em>n</em> elements listed in <em>args</em>.</p> <p class="deprecated"> <span class="versionmodified">Deprecated since version 3.0:</span> Use <a class="reference internal" href="#inspect.getfullargspec" title="inspect.getfullargspec"><tt class="xref py py-func docutils literal"><span class="pre">getfullargspec()</span></tt></a> instead, which provides information about keyword-only arguments and annotations.</p> </dd></dl> <dl class="function"> <dt id="inspect.getfullargspec"> <tt class="descclassname">inspect.</tt><tt class="descname">getfullargspec</tt><big>(</big><em>func</em><big>)</big><a class="headerlink" href="#inspect.getfullargspec" title="Permalink to this definition">¶</a></dt> <dd><p>Get the names and default values of a Python function’s arguments. A <a class="reference internal" href="../glossary.html#term-named-tuple"><em class="xref std std-term">named tuple</em></a> is returned:</p> <p><tt class="docutils literal"><span class="pre">FullArgSpec(args,</span> <span class="pre">varargs,</span> <span class="pre">varkw,</span> <span class="pre">defaults,</span> <span class="pre">kwonlyargs,</span> <span class="pre">kwonlydefaults,</span> <span class="pre">annotations)</span></tt></p> <p><em>args</em> is a list of the argument names. <em>varargs</em> and <em>varkw</em> are the names of the <tt class="docutils literal"><span class="pre">*</span></tt> and <tt class="docutils literal"><span class="pre">**</span></tt> arguments or <tt class="xref docutils literal"><span class="pre">None</span></tt>. <em>defaults</em> is an <em>n</em>-tuple of the default values of the last <em>n</em> arguments, or <tt class="xref docutils literal"><span class="pre">None</span></tt> if there are no default arguments. <em>kwonlyargs</em> is a list of keyword-only argument names. <em>kwonlydefaults</em> is a dictionary mapping names from kwonlyargs to defaults. <em>annotations</em> is a dictionary mapping argument names to annotations.</p> <p>The first four items in the tuple correspond to <a class="reference internal" href="#inspect.getargspec" title="inspect.getargspec"><tt class="xref py py-func docutils literal"><span class="pre">getargspec()</span></tt></a>.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">Consider using the new <a class="reference internal" href="#inspect-signature-object"><em>Signature Object</em></a> interface, which provides a better way of introspecting functions.</p> </div> </dd></dl> <dl class="function"> <dt id="inspect.getargvalues"> <tt class="descclassname">inspect.</tt><tt class="descname">getargvalues</tt><big>(</big><em>frame</em><big>)</big><a class="headerlink" href="#inspect.getargvalues" title="Permalink to this definition">¶</a></dt> <dd><p>Get information about arguments passed into a particular frame. A <a class="reference internal" href="../glossary.html#term-named-tuple"><em class="xref std std-term">named tuple</em></a> <tt class="docutils literal"><span class="pre">ArgInfo(args,</span> <span class="pre">varargs,</span> <span class="pre">keywords,</span> <span class="pre">locals)</span></tt> is returned. <em>args</em> is a list of the argument names. <em>varargs</em> and <em>keywords</em> are the names of the <tt class="docutils literal"><span class="pre">*</span></tt> and <tt class="docutils literal"><span class="pre">**</span></tt> arguments or <tt class="xref docutils literal"><span class="pre">None</span></tt>. <em>locals</em> is the locals dictionary of the given frame.</p> </dd></dl> <dl class="function"> <dt id="inspect.formatargspec"> <tt class="descclassname">inspect.</tt><tt class="descname">formatargspec</tt><big>(</big><em>args</em><span class="optional">[</span>, <em>varargs</em>, <em>varkw</em>, <em>defaults</em>, <em>kwonlyargs</em>, <em>kwonlydefaults</em>, <em>annotations</em><span class="optional">[</span>, <em>formatarg</em>, <em>formatvarargs</em>, <em>formatvarkw</em>, <em>formatvalue</em>, <em>formatreturns</em>, <em>formatannotations</em><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#inspect.formatargspec" title="Permalink to this definition">¶</a></dt> <dd><p>Format a pretty argument spec from the values returned by <a class="reference internal" href="#inspect.getargspec" title="inspect.getargspec"><tt class="xref py py-func docutils literal"><span class="pre">getargspec()</span></tt></a> or <a class="reference internal" href="#inspect.getfullargspec" title="inspect.getfullargspec"><tt class="xref py py-func docutils literal"><span class="pre">getfullargspec()</span></tt></a>.</p> <p>The first seven arguments are (<tt class="docutils literal"><span class="pre">args</span></tt>, <tt class="docutils literal"><span class="pre">varargs</span></tt>, <tt class="docutils literal"><span class="pre">varkw</span></tt>, <tt class="docutils literal"><span class="pre">defaults</span></tt>, <tt class="docutils literal"><span class="pre">kwonlyargs</span></tt>, <tt class="docutils literal"><span class="pre">kwonlydefaults</span></tt>, <tt class="docutils literal"><span class="pre">annotations</span></tt>). The other five arguments are the corresponding optional formatting functions that are called to turn names and values into strings. The last argument is an optional function to format the sequence of arguments. For example:</p> <div class="highlight-python3"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">inspect</span> <span class="k">import</span> <span class="n">formatargspec</span><span class="p">,</span> <span class="n">getfullargspec</span> <span class="gp">>>> </span><span class="k">def</span> <span class="nf">f</span><span class="p">(</span><span class="n">a</span><span class="p">:</span> <span class="nb">int</span><span class="p">,</span> <span class="n">b</span><span class="p">:</span> <span class="nb">float</span><span class="p">):</span> <span class="gp">... </span> <span class="k">pass</span> <span class="gp">...</span> <span class="gp">>>> </span><span class="n">formatargspec</span><span class="p">(</span><span class="o">*</span><span class="n">getfullargspec</span><span class="p">(</span><span class="n">f</span><span class="p">))</span> <span class="go">'(a: int, b: float)'</span> </pre></div> </div> </dd></dl> <dl class="function"> <dt id="inspect.formatargvalues"> <tt class="descclassname">inspect.</tt><tt class="descname">formatargvalues</tt><big>(</big><em>args</em><span class="optional">[</span>, <em>varargs</em>, <em>varkw</em>, <em>locals</em>, <em>formatarg</em>, <em>formatvarargs</em>, <em>formatvarkw</em>, <em>formatvalue</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#inspect.formatargvalues" title="Permalink to this definition">¶</a></dt> <dd><p>Format a pretty argument spec from the four values returned by <a class="reference internal" href="#inspect.getargvalues" title="inspect.getargvalues"><tt class="xref py py-func docutils literal"><span class="pre">getargvalues()</span></tt></a>. The format* arguments are the corresponding optional formatting functions that are called to turn names and values into strings.</p> </dd></dl> <dl class="function"> <dt id="inspect.getmro"> <tt class="descclassname">inspect.</tt><tt class="descname">getmro</tt><big>(</big><em>cls</em><big>)</big><a class="headerlink" href="#inspect.getmro" title="Permalink to this definition">¶</a></dt> <dd><p>Return a tuple of class cls’s base classes, including cls, in method resolution order. No class appears more than once in this tuple. Note that the method resolution order depends on cls’s type. Unless a very peculiar user-defined metatype is in use, cls will be the first element of the tuple.</p> </dd></dl> <dl class="function"> <dt id="inspect.getcallargs"> <tt class="descclassname">inspect.</tt><tt class="descname">getcallargs</tt><big>(</big><em>func[, *args][, **kwds]</em><big>)</big><a class="headerlink" href="#inspect.getcallargs" title="Permalink to this definition">¶</a></dt> <dd><p>Bind the <em>args</em> and <em>kwds</em> to the argument names of the Python function or method <em>func</em>, as if it was called with them. For bound methods, bind also the first argument (typically named <tt class="docutils literal"><span class="pre">self</span></tt>) to the associated instance. A dict is returned, mapping the argument names (including the names of the <tt class="docutils literal"><span class="pre">*</span></tt> and <tt class="docutils literal"><span class="pre">**</span></tt> arguments, if any) to their values from <em>args</em> and <em>kwds</em>. In case of invoking <em>func</em> incorrectly, i.e. whenever <tt class="docutils literal"><span class="pre">func(*args,</span> <span class="pre">**kwds)</span></tt> would raise an exception because of incompatible signature, an exception of the same type and the same or similar message is raised. For example:</p> <div class="highlight-python3"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">inspect</span> <span class="k">import</span> <span class="n">getcallargs</span> <span class="gp">>>> </span><span class="k">def</span> <span class="nf">f</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span> <span class="o">*</span><span class="n">pos</span><span class="p">,</span> <span class="o">**</span><span class="n">named</span><span class="p">):</span> <span class="gp">... </span> <span class="k">pass</span> <span class="gp">>>> </span><span class="n">getcallargs</span><span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span> <span class="o">==</span> <span class="p">{</span><span class="s">'a'</span><span class="p">:</span> <span class="mi">1</span><span class="p">,</span> <span class="s">'named'</span><span class="p">:</span> <span class="p">{},</span> <span class="s">'b'</span><span class="p">:</span> <span class="mi">2</span><span class="p">,</span> <span class="s">'pos'</span><span class="p">:</span> <span class="p">(</span><span class="mi">3</span><span class="p">,)}</span> <span class="go">True</span> <span class="gp">>>> </span><span class="n">getcallargs</span><span class="p">(</span><span class="n">f</span><span class="p">,</span> <span class="n">a</span><span class="o">=</span><span class="mi">2</span><span class="p">,</span> <span class="n">x</span><span class="o">=</span><span class="mi">4</span><span class="p">)</span> <span class="o">==</span> <span class="p">{</span><span class="s">'a'</span><span class="p">:</span> <span class="mi">2</span><span class="p">,</span> <span class="s">'named'</span><span class="p">:</span> <span class="p">{</span><span class="s">'x'</span><span class="p">:</span> <span class="mi">4</span><span class="p">},</span> <span class="s">'b'</span><span class="p">:</span> <span class="mi">1</span><span class="p">,</span> <span class="s">'pos'</span><span class="p">:</span> <span class="p">()}</span> <span class="go">True</span> <span class="gp">>>> </span><span class="n">getcallargs</span><span class="p">(</span><span class="n">f</span><span class="p">)</span> <span class="gt">Traceback (most recent call last):</span> <span class="c">...</span> <span class="gr">TypeError: f() missing 1 required positional argument</span>: <span class="n">'a'</span> </pre></div> </div> <p class="versionadded"> <span class="versionmodified">New in version 3.2.</span> </p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">Consider using the new <a class="reference internal" href="#inspect.Signature.bind" title="inspect.Signature.bind"><tt class="xref py py-meth docutils literal"><span class="pre">Signature.bind()</span></tt></a> instead.</p> </div> </dd></dl> <dl class="function"> <dt id="inspect.getclosurevars"> <tt class="descclassname">inspect.</tt><tt class="descname">getclosurevars</tt><big>(</big><em>func</em><big>)</big><a class="headerlink" href="#inspect.getclosurevars" title="Permalink to this definition">¶</a></dt> <dd><p>Get the mapping of external name references in a Python function or method <em>func</em> to their current values. A <a class="reference internal" href="../glossary.html#term-named-tuple"><em class="xref std std-term">named tuple</em></a> <tt class="docutils literal"><span class="pre">ClosureVars(nonlocals,</span> <span class="pre">globals,</span> <span class="pre">builtins,</span> <span class="pre">unbound)</span></tt> is returned. <em>nonlocals</em> maps referenced names to lexical closure variables, <em>globals</em> to the function’s module globals and <em>builtins</em> to the builtins visible from the function body. <em>unbound</em> is the set of names referenced in the function that could not be resolved at all given the current module globals and builtins.</p> <p><a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><tt class="xref py py-exc docutils literal"><span class="pre">TypeError</span></tt></a> is raised if <em>func</em> is not a Python function or method.</p> <p class="versionadded"> <span class="versionmodified">New in version 3.3.</span> </p> </dd></dl> </div> <div class="section" id="the-interpreter-stack"> <span id="inspect-stack"></span><h2>28.12.5. The interpreter stack<a class="headerlink" href="#the-interpreter-stack" title="Permalink to this headline">¶</a></h2> <p>When the following functions return “frame records,” each record is a tuple of six items: the frame object, the filename, the line number of the current line, the function name, a list of lines of context from the source code, and the index of the current line within that list.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p>Keeping references to frame objects, as found in the first element of the frame records these functions return, can cause your program to create reference cycles. Once a reference cycle has been created, the lifespan of all objects which can be accessed from the objects which form the cycle can become much longer even if Python’s optional cycle detector is enabled. If such cycles must be created, it is important to ensure they are explicitly broken to avoid the delayed destruction of objects and increased memory consumption which occurs.</p> <p>Though the cycle detector will catch these, destruction of the frames (and local variables) can be made deterministic by removing the cycle in a <a class="reference internal" href="../reference/compound_stmts.html#finally"><tt class="xref std std-keyword docutils literal"><span class="pre">finally</span></tt></a> clause. This is also important if the cycle detector was disabled when Python was compiled or using <a class="reference internal" href="gc.html#gc.disable" title="gc.disable"><tt class="xref py py-func docutils literal"><span class="pre">gc.disable()</span></tt></a>. For example:</p> <div class="last highlight-python3"><div class="highlight"><pre><span class="k">def</span> <span class="nf">handle_stackframe_without_leak</span><span class="p">():</span> <span class="n">frame</span> <span class="o">=</span> <span class="n">inspect</span><span class="o">.</span><span class="n">currentframe</span><span class="p">()</span> <span class="k">try</span><span class="p">:</span> <span class="c"># do something with the frame</span> <span class="k">finally</span><span class="p">:</span> <span class="k">del</span> <span class="n">frame</span> </pre></div> </div> </div> <p>The optional <em>context</em> argument supported by most of these functions specifies the number of lines of context to return, which are centered around the current line.</p> <dl class="function"> <dt id="inspect.getframeinfo"> <tt class="descclassname">inspect.</tt><tt class="descname">getframeinfo</tt><big>(</big><em>frame</em>, <em>context=1</em><big>)</big><a class="headerlink" href="#inspect.getframeinfo" title="Permalink to this definition">¶</a></dt> <dd><p>Get information about a frame or traceback object. A <a class="reference internal" href="../glossary.html#term-named-tuple"><em class="xref std std-term">named tuple</em></a> <tt class="docutils literal"><span class="pre">Traceback(filename,</span> <span class="pre">lineno,</span> <span class="pre">function,</span> <span class="pre">code_context,</span> <span class="pre">index)</span></tt> is returned.</p> </dd></dl> <dl class="function"> <dt id="inspect.getouterframes"> <tt class="descclassname">inspect.</tt><tt class="descname">getouterframes</tt><big>(</big><em>frame</em>, <em>context=1</em><big>)</big><a class="headerlink" href="#inspect.getouterframes" title="Permalink to this definition">¶</a></dt> <dd><p>Get a list of frame records for a frame and all outer frames. These frames represent the calls that lead to the creation of <em>frame</em>. The first entry in the returned list represents <em>frame</em>; the last entry represents the outermost call on <em>frame</em>‘s stack.</p> </dd></dl> <dl class="function"> <dt id="inspect.getinnerframes"> <tt class="descclassname">inspect.</tt><tt class="descname">getinnerframes</tt><big>(</big><em>traceback</em>, <em>context=1</em><big>)</big><a class="headerlink" href="#inspect.getinnerframes" title="Permalink to this definition">¶</a></dt> <dd><p>Get a list of frame records for a traceback’s frame and all inner frames. These frames represent calls made as a consequence of <em>frame</em>. The first entry in the list represents <em>traceback</em>; the last entry represents where the exception was raised.</p> </dd></dl> <dl class="function"> <dt id="inspect.currentframe"> <tt class="descclassname">inspect.</tt><tt class="descname">currentframe</tt><big>(</big><big>)</big><a class="headerlink" href="#inspect.currentframe" title="Permalink to this definition">¶</a></dt> <dd><p>Return the frame object for the caller’s stack frame.</p> <div class="impl-detail compound"> <p><strong>CPython implementation detail:</strong> This function relies on Python stack frame support in the interpreter, which isn’t guaranteed to exist in all implementations of Python. If running in an implementation without Python stack frame support this function returns <tt class="xref docutils literal"><span class="pre">None</span></tt>.</p> </div> </dd></dl> <dl class="function"> <dt id="inspect.stack"> <tt class="descclassname">inspect.</tt><tt class="descname">stack</tt><big>(</big><em>context=1</em><big>)</big><a class="headerlink" href="#inspect.stack" title="Permalink to this definition">¶</a></dt> <dd><p>Return a list of frame records for the caller’s stack. The first entry in the returned list represents the caller; the last entry represents the outermost call on the stack.</p> </dd></dl> <dl class="function"> <dt id="inspect.trace"> <tt class="descclassname">inspect.</tt><tt class="descname">trace</tt><big>(</big><em>context=1</em><big>)</big><a class="headerlink" href="#inspect.trace" title="Permalink to this definition">¶</a></dt> <dd><p>Return a list of frame records for the stack between the current frame and the frame in which an exception currently being handled was raised in. The first entry in the list represents the caller; the last entry represents where the exception was raised.</p> </dd></dl> </div> <div class="section" id="fetching-attributes-statically"> <h2>28.12.6. Fetching attributes statically<a class="headerlink" href="#fetching-attributes-statically" title="Permalink to this headline">¶</a></h2> <p>Both <a class="reference internal" href="functions.html#getattr" title="getattr"><tt class="xref py py-func docutils literal"><span class="pre">getattr()</span></tt></a> and <a class="reference internal" href="functions.html#hasattr" title="hasattr"><tt class="xref py py-func docutils literal"><span class="pre">hasattr()</span></tt></a> can trigger code execution when fetching or checking for the existence of attributes. Descriptors, like properties, will be invoked and <a class="reference internal" href="../reference/datamodel.html#object.__getattr__" title="object.__getattr__"><tt class="xref py py-meth docutils literal"><span class="pre">__getattr__()</span></tt></a> and <a class="reference internal" href="../reference/datamodel.html#object.__getattribute__" title="object.__getattribute__"><tt class="xref py py-meth docutils literal"><span class="pre">__getattribute__()</span></tt></a> may be called.</p> <p>For cases where you want passive introspection, like documentation tools, this can be inconvenient. <a class="reference internal" href="#inspect.getattr_static" title="inspect.getattr_static"><tt class="xref py py-func docutils literal"><span class="pre">getattr_static()</span></tt></a> has the same signature as <a class="reference internal" href="functions.html#getattr" title="getattr"><tt class="xref py py-func docutils literal"><span class="pre">getattr()</span></tt></a> but avoids executing code when it fetches attributes.</p> <dl class="function"> <dt id="inspect.getattr_static"> <tt class="descclassname">inspect.</tt><tt class="descname">getattr_static</tt><big>(</big><em>obj</em>, <em>attr</em>, <em>default=None</em><big>)</big><a class="headerlink" href="#inspect.getattr_static" title="Permalink to this definition">¶</a></dt> <dd><p>Retrieve attributes without triggering dynamic lookup via the descriptor protocol, <a class="reference internal" href="../reference/datamodel.html#object.__getattr__" title="object.__getattr__"><tt class="xref py py-meth docutils literal"><span class="pre">__getattr__()</span></tt></a> or <a class="reference internal" href="../reference/datamodel.html#object.__getattribute__" title="object.__getattribute__"><tt class="xref py py-meth docutils literal"><span class="pre">__getattribute__()</span></tt></a>.</p> <p>Note: this function may not be able to retrieve all attributes that getattr can fetch (like dynamically created attributes) and may find attributes that getattr can’t (like descriptors that raise AttributeError). It can also return descriptors objects instead of instance members.</p> <p>If the instance <tt class="xref py py-attr docutils literal"><span class="pre">__dict__</span></tt> is shadowed by another member (for example a property) then this function will be unable to find instance members.</p> <p class="versionadded"> <span class="versionmodified">New in version 3.2.</span> </p> </dd></dl> <p><a class="reference internal" href="#inspect.getattr_static" title="inspect.getattr_static"><tt class="xref py py-func docutils literal"><span class="pre">getattr_static()</span></tt></a> does not resolve descriptors, for example slot descriptors or getset descriptors on objects implemented in C. The descriptor object is returned instead of the underlying attribute.</p> <p>You can handle these with code like the following. Note that for arbitrary getset descriptors invoking these may trigger code execution:</p> <div class="highlight-python3"><div class="highlight"><pre><span class="c"># example code for resolving the builtin descriptor types</span> <span class="k">class</span> <span class="nc">_foo</span><span class="p">:</span> <span class="n">__slots__</span> <span class="o">=</span> <span class="p">[</span><span class="s">'foo'</span><span class="p">]</span> <span class="n">slot_descriptor</span> <span class="o">=</span> <span class="nb">type</span><span class="p">(</span><span class="n">_foo</span><span class="o">.</span><span class="n">foo</span><span class="p">)</span> <span class="n">getset_descriptor</span> <span class="o">=</span> <span class="nb">type</span><span class="p">(</span><span class="nb">type</span><span class="p">(</span><span class="nb">open</span><span class="p">(</span><span class="n">__file__</span><span class="p">))</span><span class="o">.</span><span class="n">name</span><span class="p">)</span> <span class="n">wrapper_descriptor</span> <span class="o">=</span> <span class="nb">type</span><span class="p">(</span><span class="nb">str</span><span class="o">.</span><span class="n">__dict__</span><span class="p">[</span><span class="s">'__add__'</span><span class="p">])</span> <span class="n">descriptor_types</span> <span class="o">=</span> <span class="p">(</span><span class="n">slot_descriptor</span><span class="p">,</span> <span class="n">getset_descriptor</span><span class="p">,</span> <span class="n">wrapper_descriptor</span><span class="p">)</span> <span class="n">result</span> <span class="o">=</span> <span class="n">getattr_static</span><span class="p">(</span><span class="n">some_object</span><span class="p">,</span> <span class="s">'foo'</span><span class="p">)</span> <span class="k">if</span> <span class="nb">type</span><span class="p">(</span><span class="n">result</span><span class="p">)</span> <span class="ow">in</span> <span class="n">descriptor_types</span><span class="p">:</span> <span class="k">try</span><span class="p">:</span> <span class="n">result</span> <span class="o">=</span> <span class="n">result</span><span class="o">.</span><span class="n">__get__</span><span class="p">()</span> <span class="k">except</span> <span class="ne">AttributeError</span><span class="p">:</span> <span class="c"># descriptors can raise AttributeError to</span> <span class="c"># indicate there is no underlying value</span> <span class="c"># in which case the descriptor itself will</span> <span class="c"># have to do</span> <span class="k">pass</span> </pre></div> </div> </div> <div class="section" id="current-state-of-a-generator"> <h2>28.12.7. Current State of a Generator<a class="headerlink" href="#current-state-of-a-generator" title="Permalink to this headline">¶</a></h2> <p>When implementing coroutine schedulers and for other advanced uses of generators, it is useful to determine whether a generator is currently executing, is waiting to start or resume or execution, or has already terminated. <a class="reference internal" href="#inspect.getgeneratorstate" title="inspect.getgeneratorstate"><tt class="xref py py-func docutils literal"><span class="pre">getgeneratorstate()</span></tt></a> allows the current state of a generator to be determined easily.</p> <dl class="function"> <dt id="inspect.getgeneratorstate"> <tt class="descclassname">inspect.</tt><tt class="descname">getgeneratorstate</tt><big>(</big><em>generator</em><big>)</big><a class="headerlink" href="#inspect.getgeneratorstate" title="Permalink to this definition">¶</a></dt> <dd><p>Get current state of a generator-iterator.</p> <dl class="docutils"> <dt>Possible states are:</dt> <dd><ul class="first last simple"> <li>GEN_CREATED: Waiting to start execution.</li> <li>GEN_RUNNING: Currently being executed by the interpreter.</li> <li>GEN_SUSPENDED: Currently suspended at a yield expression.</li> <li>GEN_CLOSED: Execution has completed.</li> </ul> </dd> </dl> <p class="versionadded"> <span class="versionmodified">New in version 3.2.</span> </p> </dd></dl> <p>The current internal state of the generator can also be queried. This is mostly useful for testing purposes, to ensure that internal state is being updated as expected:</p> <dl class="function"> <dt id="inspect.getgeneratorlocals"> <tt class="descclassname">inspect.</tt><tt class="descname">getgeneratorlocals</tt><big>(</big><em>generator</em><big>)</big><a class="headerlink" href="#inspect.getgeneratorlocals" title="Permalink to this definition">¶</a></dt> <dd><p>Get the mapping of live local variables in <em>generator</em> to their current values. A dictionary is returned that maps from variable names to values. This is the equivalent of calling <a class="reference internal" href="functions.html#locals" title="locals"><tt class="xref py py-func docutils literal"><span class="pre">locals()</span></tt></a> in the body of the generator, and all the same caveats apply.</p> <p>If <em>generator</em> is a <a class="reference internal" href="../glossary.html#term-generator"><em class="xref std std-term">generator</em></a> with no currently associated frame, then an empty dictionary is returned. <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><tt class="xref py py-exc docutils literal"><span class="pre">TypeError</span></tt></a> is raised if <em>generator</em> is not a Python generator object.</p> <div class="impl-detail compound"> <p><strong>CPython implementation detail:</strong> This function relies on the generator exposing a Python stack frame for introspection, which isn’t guaranteed to be the case in all implementations of Python. In such cases, this function will always return an empty dictionary.</p> </div> <p class="versionadded"> <span class="versionmodified">New in version 3.3.</span> </p> </dd></dl> </div> </div> </div> </div> </div> <div class="sphinxsidebar"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table Of Contents</a></h3> <ul> <li><a class="reference internal" href="#">28.12. <tt class="docutils literal"><span class="pre">inspect</span></tt> — Inspect live objects</a><ul> <li><a class="reference internal" href="#types-and-members">28.12.1. Types and members</a></li> <li><a class="reference internal" href="#retrieving-source-code">28.12.2. Retrieving source code</a></li> <li><a class="reference internal" href="#introspecting-callables-with-the-signature-object">28.12.3. Introspecting callables with the Signature object</a></li> <li><a class="reference internal" href="#classes-and-functions">28.12.4. Classes and functions</a></li> <li><a class="reference internal" href="#the-interpreter-stack">28.12.5. The interpreter stack</a></li> <li><a class="reference internal" href="#fetching-attributes-statically">28.12.6. Fetching attributes statically</a></li> <li><a class="reference internal" href="#current-state-of-a-generator">28.12.7. Current State of a Generator</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="gc.html" title="previous chapter">28.11. <tt class="docutils literal docutils literal docutils literal"><span class="pre">gc</span></tt> — Garbage Collector interface</a></p> <h4>Next topic</h4> <p class="topless"><a href="site.html" title="next chapter">28.13. <tt class="docutils literal docutils literal"><span class="pre">site</span></tt> — Site-specific configuration hook</a></p> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li><a href="../_sources/library/inspect.txt" rel="nofollow">Show Source</a></li> </ul> <div id="searchbox" style="display: none"> <h3>Quick search</h3> <form class="search" action="../search.html" method="get"> <input type="text" name="q" size="18" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> <p class="searchtip" style="font-size: 90%"> Enter search terms or a module, class or function name. </p> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <div class="clearer"></div> </div> <div class="related"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="site.html" title="28.13. site — Site-specific configuration hook" >next</a> |</li> <li class="right" > <a href="gc.html" title="28.11. gc — Garbage Collector interface" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="http://www.python.org/">Python</a> »</li> <li> <a href="../index.html">3.3.2 Documentation</a> » </li> <li><a href="index.html" >The Python Standard Library</a> »</li> <li><a href="python.html" >28. Python Runtime Services</a> »</li> </ul> </div> <div class="footer"> © <a href="../copyright.html">Copyright</a> 1990-2013, Python Software Foundation. <br /> The Python Software Foundation is a non-profit corporation. <a href="http://www.python.org/psf/donations/">Please donate.</a> <br /> Last updated on May 15, 2013. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.0.7. </div> </body> </html>