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<div class="section" id="general-advices-and-troubleshooting">
<h1>General advices and troubleshooting<a class="headerlink" href="#general-advices-and-troubleshooting" title="Permalink to this headline">¶</a></h1>
<div class="contents local topic" id="contents">
<ul class="simple">
<li><a class="reference internal" href="#getting-code-samples" id="id1">Getting code samples</a></li>
<li><a class="reference internal" href="#use-the-logging-system" id="id2">Use the logging system</a></li>
<li><a class="reference internal" href="#categorization-by-inheritance-caveat" id="id3">Categorization by inheritance caveat</a></li>
<li><a class="reference internal" href="#plugin-class-detection-caveat" id="id4">Plugin class detection caveat</a></li>
<li><a class="reference internal" href="#plugin-packaging" id="id5">Plugin packaging</a></li>
<li><a class="reference internal" href="#code-conventions" id="id6">Code conventions</a></li>
</ul>
</div>
<div class="section" id="getting-code-samples">
<h2><a class="toc-backref" href="#id1">Getting code samples</a><a class="headerlink" href="#getting-code-samples" title="Permalink to this headline">¶</a></h2>
<p>Yapsy is used enough for your favorite search provider to have good
chances of finding some examples of yapsy being used in the wild.</p>
<p>However if you wonder how a specific functionality can be used, you
can also look at the corresponding unit test (in the test folder
packaged with yapsy’s sources).</p>
</div>
<div class="section" id="use-the-logging-system">
<h2><a class="toc-backref" href="#id2">Use the logging system</a><a class="headerlink" href="#use-the-logging-system" title="Permalink to this headline">¶</a></h2>
<p>Yapsy uses Python’s standard <tt class="docutils literal"><span class="pre">logging</span></tt> module to record most
important events and especially plugin loading failures.</p>
<p>When developping an application based on yapsy, you’ll benefit from
looking at the ‘debug’ level logs, which can easily be done from your
application code with the following snippet:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">logging</span>
<span class="n">logging</span><span class="o">.</span><span class="n">basicConfig</span><span class="p">(</span><span class="n">level</span><span class="o">=</span><span class="n">logging</span><span class="o">.</span><span class="n">DEBUG</span><span class="p">)</span>
</pre></div>
</div>
<p>Also, please note that yapsy uses a named logger for all its logs, so
that you can selectively activage debug logs for yapsy with the
following snippet:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">logging</span>
<span class="n">logging</span><span class="o">.</span><span class="n">getLogger</span><span class="p">(</span><span class="s">'yapsy'</span><span class="p">)</span><span class="o">.</span><span class="n">setLevel</span><span class="p">(</span><span class="n">logging</span><span class="o">.</span><span class="n">DEBUG</span><span class="p">)</span>
</pre></div>
</div>
</div>
<div class="section" id="categorization-by-inheritance-caveat">
<h2><a class="toc-backref" href="#id3">Categorization by inheritance caveat</a><a class="headerlink" href="#categorization-by-inheritance-caveat" title="Permalink to this headline">¶</a></h2>
<p>If your application defines various categories of plugins with the yapsy’s built-in mechanism for that, please keep in mind the following facts:</p>
<blockquote>
<div><ul class="simple">
<li>a plugin instance is attributed to a given category by looking if
it is an instance, <em>even via a subclass</em>, of the class associated
to this category;</li>
<li>a plugin may be attributed to several categories.</li>
</ul>
</div></blockquote>
<p>Considering this, and if you consider using several categories, you
should consider the following tips:</p>
<blockquote>
<div><ul class="simple">
<li><strong>don’t associate any category to ``IPlugin``</strong> (unless you want
all plugins to be attributed to the corresponding category)</li>
<li><strong>design a specific subclass</strong> of <tt class="docutils literal"><span class="pre">IPlugin</span></tt> for each category</li>
<li>if you want to regroup plugins of some categories into a common
category: do this by attributing a subclass of <tt class="docutils literal"><span class="pre">IPlugin</span></tt> to the
common category and attribute to the other categories specific
subclasses to this intermediate mother class so that <strong>the plugin
class inheritance hierarchy reflects the hierarchy between
categories</strong> (and if you want something more complex that a
hierarchy, you can consider using mixins).</li>
</ul>
</div></blockquote>
</div>
<div class="section" id="plugin-class-detection-caveat">
<h2><a class="toc-backref" href="#id4">Plugin class detection caveat</a><a class="headerlink" href="#plugin-class-detection-caveat" title="Permalink to this headline">¶</a></h2>
<p>Because of the “categorization by inheritance” system, you <strong>musn’t
directly import the subclass</strong> of <tt class="docutils literal"><span class="pre">IPlugin</span></tt> in the main plugin file,
instead import its containing module and make your plugin class
inherit from <tt class="docutils literal"><span class="pre">ContainingModule.SpecificPluginClass</span></tt> as in the
following example.</p>
<p>The following code won’t work (the class <tt class="docutils literal"><span class="pre">MyBasePluginClass</span></tt> will be
detected as the plugin’s implementation instead of <tt class="docutils literal"><span class="pre">MyPlugin</span></tt>):</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">myapp.plugintypes</span> <span class="kn">import</span> <span class="n">MyBasePluginClass</span>
<span class="k">class</span> <span class="nc">MyPlugin</span><span class="p">(</span><span class="n">MyBasePluginClass</span><span class="p">):</span>
<span class="k">pass</span>
</pre></div>
</div>
<p>Instead you should do the following:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">myapp.plugintypes</span> <span class="kn">as</span> <span class="nn">plugintypes</span>
<span class="k">class</span> <span class="nc">MyPlugin</span><span class="p">(</span><span class="n">plugintypes</span><span class="o">.</span><span class="n">MyBasePluginClass</span><span class="p">):</span>
<span class="k">pass</span>
</pre></div>
</div>
</div>
<div class="section" id="plugin-packaging">
<h2><a class="toc-backref" href="#id5">Plugin packaging</a><a class="headerlink" href="#plugin-packaging" title="Permalink to this headline">¶</a></h2>
<p>When packaging plugins in a distutils installer or as parts of an
application (like for instance with <cite>py2exe</cite>), you may want to take
care about the following points:</p>
<ul class="simple">
<li>when you set specific directories where to look for plugins with a
hardcoded path, be very carefully about the way you write these
paths because depending on the cases <strong>using ``__file__`` or
relative paths may be unreliable</strong>. For instance with py2exe, you
may want to follow the tips from the <a class="reference external" href="http://www.py2exe.org/index.cgi/WhereAmI">Where Am I FAQ</a>.</li>
<li>you’d should either <strong>package the plugins as plain Python modules or
data files</strong> (if you want to consider you application as the only
module), either using the dedicated <cite>setup</cite> argument for <cite>py2exe</cite> or
using distutils’ <cite>MANIFEST.in</cite></li>
<li>if you do package the plugins as data files, <strong>make sure that their
dependencies are correctly indicated as dependencies of your
package</strong> (or packaged with you application if you use <cite>py2exe</cite>).</li>
</ul>
<p>See also a more detailed example for py2exe on <a class="reference external" href="http://notinthestars.blogspot.com.es/2011/04/using-python-plugin-scripts-with-py2exe.html">Simon on Tech’s Using python plugin scripts with py2exe</a>.</p>
</div>
<div class="section" id="code-conventions">
<h2><a class="toc-backref" href="#id6">Code conventions</a><a class="headerlink" href="#code-conventions" title="Permalink to this headline">¶</a></h2>
<p>If you intend to modify yapsy’s sources and to contribute patches
back, please respect the following conventions:</p>
<ul class="simple">
<li>CamelCase (upper camel case) for class names and functions</li>
<li>camelCase (lower camel case) for methods</li>
<li>UPPERCASE for global variables (with a few exceptions)</li>
<li>tabulations are used for indentation (and not spaces !)</li>
<li>unit-test each new functionality</li>
</ul>
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<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">General advices and troubleshooting</a><ul>
<li><a class="reference internal" href="#getting-code-samples">Getting code samples</a></li>
<li><a class="reference internal" href="#use-the-logging-system">Use the logging system</a></li>
<li><a class="reference internal" href="#categorization-by-inheritance-caveat">Categorization by inheritance caveat</a></li>
<li><a class="reference internal" href="#plugin-class-detection-caveat">Plugin class detection caveat</a></li>
<li><a class="reference internal" href="#plugin-packaging">Plugin packaging</a></li>
<li><a class="reference internal" href="#code-conventions">Code conventions</a></li>
</ul>
</li>
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