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<div class="section" id="file-objects">
<span id="fileobjects"></span><h1>File Objects<a class="headerlink" href="#file-objects" title="Permalink to this headline">¶</a></h1>
<p id="index-22">Python’s built-in file objects are implemented entirely on the <tt class="xref docutils literal"><span class="pre">FILE*</span></tt>
support from the C standard library. This is an implementation detail and may
change in future releases of Python.</p>
<dl class="ctype">
<dt id="PyFileObject">
<tt class="descname">PyFileObject</tt><a class="headerlink" href="#PyFileObject" title="Permalink to this definition">¶</a></dt>
<dd>This subtype of <a title="PyObject" class="reference external" href="structures.html#PyObject"><tt class="xref docutils literal"><span class="pre">PyObject</span></tt></a> represents a Python file object.</dd></dl>
<dl class="cvar">
<dt id="PyFile_Type">
<a title="PyTypeObject" class="reference external" href="type.html#PyTypeObject">PyTypeObject</a> <tt class="descname">PyFile_Type</tt><a class="headerlink" href="#PyFile_Type" title="Permalink to this definition">¶</a></dt>
<dd><p id="index-23">This instance of <a title="PyTypeObject" class="reference external" href="type.html#PyTypeObject"><tt class="xref docutils literal"><span class="pre">PyTypeObject</span></tt></a> represents the Python file type. This is
exposed to Python programs as <tt class="docutils literal"><span class="pre">file</span></tt> and <tt class="docutils literal"><span class="pre">types.FileType</span></tt>.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_Check">
int <tt class="descname">PyFile_Check</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *p</em><big>)</big><a class="headerlink" href="#PyFile_Check" title="Permalink to this definition">¶</a></dt>
<dd><p>Return true if its argument is a <a title="PyFileObject" class="reference internal" href="#PyFileObject"><tt class="xref docutils literal"><span class="pre">PyFileObject</span></tt></a> or a subtype of
<a title="PyFileObject" class="reference internal" href="#PyFileObject"><tt class="xref docutils literal"><span class="pre">PyFileObject</span></tt></a>.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 2.2: </span>Allowed subtypes to be accepted.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_CheckExact">
int <tt class="descname">PyFile_CheckExact</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *p</em><big>)</big><a class="headerlink" href="#PyFile_CheckExact" title="Permalink to this definition">¶</a></dt>
<dd><p>Return true if its argument is a <a title="PyFileObject" class="reference internal" href="#PyFileObject"><tt class="xref docutils literal"><span class="pre">PyFileObject</span></tt></a>, but not a subtype of
<a title="PyFileObject" class="reference internal" href="#PyFileObject"><tt class="xref docutils literal"><span class="pre">PyFileObject</span></tt></a>.</p>
<p class="versionadded">
<span class="versionmodified">New in version 2.2.</span></p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_FromString">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyFile_FromString</tt><big>(</big>char<em> *filename</em>, char<em> *mode</em><big>)</big><a class="headerlink" href="#PyFile_FromString" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p id="index-24">On success, return a new file object that is opened on the file given by
<em>filename</em>, with a file mode given by <em>mode</em>, where <em>mode</em> has the same
semantics as the standard C routine <tt class="xref docutils literal"><span class="pre">fopen()</span></tt>. On failure, return <em>NULL</em>.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_FromFile">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyFile_FromFile</tt><big>(</big>FILE<em> *fp</em>, char<em> *name</em>, char<em> *mode</em>, int<em> (*close)(FILE*)</em><big>)</big><a class="headerlink" href="#PyFile_FromFile" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>Create a new <a title="PyFileObject" class="reference internal" href="#PyFileObject"><tt class="xref docutils literal"><span class="pre">PyFileObject</span></tt></a> from the already-open standard C file
pointer, <em>fp</em>. The function <em>close</em> will be called when the file should be
closed. Return <em>NULL</em> on failure.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_AsFile">
FILE* <tt class="descname">PyFile_AsFile</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *p</em><big>)</big><a class="headerlink" href="#PyFile_AsFile" title="Permalink to this definition">¶</a></dt>
<dd><p>Return the file object associated with <em>p</em> as a <tt class="xref docutils literal"><span class="pre">FILE*</span></tt>.</p>
<p>If the caller will ever use the returned <tt class="xref docutils literal"><span class="pre">FILE*</span></tt> object while
the GIL is released it must also call the <a title="PyFile_IncUseCount" class="reference internal" href="#PyFile_IncUseCount"><tt class="xref docutils literal"><span class="pre">PyFile_IncUseCount()</span></tt></a> and
<a title="PyFile_DecUseCount" class="reference internal" href="#PyFile_DecUseCount"><tt class="xref docutils literal"><span class="pre">PyFile_DecUseCount()</span></tt></a> functions described below as appropriate.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_IncUseCount">
void <tt class="descname">PyFile_IncUseCount</tt><big>(</big><a title="PyFileObject" class="reference internal" href="#PyFileObject">PyFileObject</a><em> *p</em><big>)</big><a class="headerlink" href="#PyFile_IncUseCount" title="Permalink to this definition">¶</a></dt>
<dd><p>Increments the PyFileObject’s internal use count to indicate
that the underlying <tt class="xref docutils literal"><span class="pre">FILE*</span></tt> is being used.
This prevents Python from calling f_close() on it from another thread.
Callers of this must call <a title="PyFile_DecUseCount" class="reference internal" href="#PyFile_DecUseCount"><tt class="xref docutils literal"><span class="pre">PyFile_DecUseCount()</span></tt></a> when they are
finished with the <tt class="xref docutils literal"><span class="pre">FILE*</span></tt>. Otherwise the file object will
never be closed by Python.</p>
<p>The GIL must be held while calling this function.</p>
<p>The suggested use is to call this after <a title="PyFile_AsFile" class="reference internal" href="#PyFile_AsFile"><tt class="xref docutils literal"><span class="pre">PyFile_AsFile()</span></tt></a> just before
you release the GIL.</p>
<p class="versionadded">
<span class="versionmodified">New in version 2.6.</span></p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_DecUseCount">
void <tt class="descname">PyFile_DecUseCount</tt><big>(</big><a title="PyFileObject" class="reference internal" href="#PyFileObject">PyFileObject</a><em> *p</em><big>)</big><a class="headerlink" href="#PyFile_DecUseCount" title="Permalink to this definition">¶</a></dt>
<dd><p>Decrements the PyFileObject’s internal unlocked_count member to
indicate that the caller is done with its own use of the <tt class="xref docutils literal"><span class="pre">FILE*</span></tt>.
This may only be called to undo a prior call to <a title="PyFile_IncUseCount" class="reference internal" href="#PyFile_IncUseCount"><tt class="xref docutils literal"><span class="pre">PyFile_IncUseCount()</span></tt></a>.</p>
<p>The GIL must be held while calling this function.</p>
<p class="versionadded">
<span class="versionmodified">New in version 2.6.</span></p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_GetLine">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyFile_GetLine</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *p</em>, int<em> n</em><big>)</big><a class="headerlink" href="#PyFile_GetLine" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p id="index-25">Equivalent to <tt class="docutils literal"><span class="pre">p.readline([n])</span></tt>, this function reads one line from the
object <em>p</em>. <em>p</em> may be a file object or any object with a <tt class="xref docutils literal"><span class="pre">readline()</span></tt>
method. If <em>n</em> is <tt class="docutils literal"><span class="pre">0</span></tt>, exactly one line is read, regardless of the length of
the line. If <em>n</em> is greater than <tt class="docutils literal"><span class="pre">0</span></tt>, no more than <em>n</em> bytes will be read
from the file; a partial line can be returned. In both cases, an empty string
is returned if the end of the file is reached immediately. If <em>n</em> is less than
<tt class="docutils literal"><span class="pre">0</span></tt>, however, one line is read regardless of length, but <a title="exceptions.EOFError" class="reference external" href="../library/exceptions.html#exceptions.EOFError"><tt class="xref docutils literal"><span class="pre">EOFError</span></tt></a> is
raised if the end of the file is reached immediately.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_Name">
<a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a>* <tt class="descname">PyFile_Name</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *p</em><big>)</big><a class="headerlink" href="#PyFile_Name" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: Borrowed reference.</em><p>Return the name of the file specified by <em>p</em> as a string object.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_SetBufSize">
void <tt class="descname">PyFile_SetBufSize</tt><big>(</big><a title="PyFileObject" class="reference internal" href="#PyFileObject">PyFileObject</a><em> *p</em>, int<em> n</em><big>)</big><a class="headerlink" href="#PyFile_SetBufSize" title="Permalink to this definition">¶</a></dt>
<dd><p id="index-26">Available on systems with <tt class="xref docutils literal"><span class="pre">setvbuf()</span></tt> only. This should only be called
immediately after file object creation.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_SetEncoding">
int <tt class="descname">PyFile_SetEncoding</tt><big>(</big><a title="PyFileObject" class="reference internal" href="#PyFileObject">PyFileObject</a><em> *p</em>, const char<em> *enc</em><big>)</big><a class="headerlink" href="#PyFile_SetEncoding" title="Permalink to this definition">¶</a></dt>
<dd><p>Set the file’s encoding for Unicode output to <em>enc</em>. Return 1 on success and 0
on failure.</p>
<p class="versionadded">
<span class="versionmodified">New in version 2.3.</span></p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_SetEncodingAndErrors">
int <tt class="descname">PyFile_SetEncodingAndErrors</tt><big>(</big><a title="PyFileObject" class="reference internal" href="#PyFileObject">PyFileObject</a><em> *p</em>, const char<em> *enc</em>, *errors<big>)</big><a class="headerlink" href="#PyFile_SetEncodingAndErrors" title="Permalink to this definition">¶</a></dt>
<dd><p>Set the file’s encoding for Unicode output to <em>enc</em>, and its error
mode to <em>err</em>. Return 1 on success and 0 on failure.</p>
<p class="versionadded">
<span class="versionmodified">New in version 2.6.</span></p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_SoftSpace">
int <tt class="descname">PyFile_SoftSpace</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *p</em>, int<em> newflag</em><big>)</big><a class="headerlink" href="#PyFile_SoftSpace" title="Permalink to this definition">¶</a></dt>
<dd><p id="index-27">This function exists for internal use by the interpreter. Set the
<tt class="xref docutils literal"><span class="pre">softspace</span></tt> attribute of <em>p</em> to <em>newflag</em> and return the previous value.
<em>p</em> does not have to be a file object for this function to work properly; any
object is supported (thought its only interesting if the <tt class="xref docutils literal"><span class="pre">softspace</span></tt>
attribute can be set). This function clears any errors, and will return <tt class="docutils literal"><span class="pre">0</span></tt>
as the previous value if the attribute either does not exist or if there were
errors in retrieving it. There is no way to detect errors from this function,
but doing so should not be needed.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_WriteObject">
int <tt class="descname">PyFile_WriteObject</tt><big>(</big><a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *obj</em>, <a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *p</em>, int<em> flags</em><big>)</big><a class="headerlink" href="#PyFile_WriteObject" title="Permalink to this definition">¶</a></dt>
<dd><p id="index-28">Write object <em>obj</em> to file object <em>p</em>. The only supported flag for <em>flags</em> is
<tt class="xref docutils literal"><span class="pre">Py_PRINT_RAW</span></tt>; if given, the <a title="str" class="reference external" href="../library/functions.html#str"><tt class="xref docutils literal"><span class="pre">str()</span></tt></a> of the object is written
instead of the <a title="repr" class="reference external" href="../library/functions.html#repr"><tt class="xref docutils literal"><span class="pre">repr()</span></tt></a>. Return <tt class="docutils literal"><span class="pre">0</span></tt> on success or <tt class="docutils literal"><span class="pre">-1</span></tt> on failure; the
appropriate exception will be set.</p>
</dd></dl>
<dl class="cfunction">
<dt id="PyFile_WriteString">
int <tt class="descname">PyFile_WriteString</tt><big>(</big>const char<em> *s</em>, <a title="PyObject" class="reference external" href="structures.html#PyObject">PyObject</a><em> *p</em><big>)</big><a class="headerlink" href="#PyFile_WriteString" title="Permalink to this definition">¶</a></dt>
<dd>Write string <em>s</em> to file object <em>p</em>. Return <tt class="docutils literal"><span class="pre">0</span></tt> on success or <tt class="docutils literal"><span class="pre">-1</span></tt> on
failure; the appropriate exception will be set.</dd></dl>
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