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you know what this paragraph needs? less detail.

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Mark Pilgrim
2010-07-30 10:12:56 -04:00
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@@ -184,7 +184,7 @@ SyntaxError: non-keyword arg after keyword arg</samp></pre>
<ol>
<li>Importing the <code>sys</code> module makes all of its functions and attributes available.
<li><code>sys.path</code> is a list of directory names that constitute the current search path. (Yours will look different, depending on your operating system, what version of Python you&#8217;re running, and where it was originally installed.) Python will look through these directories (in this order) for a <code>.py</code> file whose name matches what you&#8217;re trying to import.
<li>Actually, I lied; the truth is more complicated than that, because not all modules are stored as <code>.py</code> files. Some, like the <code>sys</code> module, are <i>built-in modules</i>; they are actually baked right into Python itself. Built-in modules behave just like regular modules, but their Python source code is not available, because they are not written in Python! (The <code>sys</code> module is written in <abbr>C</abbr>.)
<li>Actually, I lied; the truth is more complicated than that, because not all modules are stored as <code>.py</code> files. Some are <i>built-in modules</i>; they are actually baked right into Python itself. Built-in modules behave just like regular modules, but their Python source code is not available, because they are not written in Python! (Like Python itself, these built-in modules are written in C.)
<li>You can add a new directory to Python&#8217;s search path at runtime by adding the directory name to <code>sys.path</code>, and then Python will look in that directory as well, whenever you try to import a module. The effect lasts as long as Python is running.
<li>By using <code>sys.path.insert(0, <var>new_path</var>)</code>, you inserted a new directory as the first item of the <code>sys.path</code> list, and therefore at the beginning of Python&#8217;s search path. This is almost always what you want. In case of naming conflicts (for example, if Python ships with version 2 of a particular library but you want to use version 3), this ensures that your modules will be found and used instead of the modules that came with Python.
</ol>