Most viewed recipes tagged "chainmap"http://code.activestate.com/recipes/tags/chainmap/views/2012-10-03T18:12:50-07:00ActiveState Code RecipesUsing ChainMap for embedded namespaces (Python)
2012-10-03T18:12:50-07:00Steven D'Apranohttp://code.activestate.com/recipes/users/4172944/http://code.activestate.com/recipes/578279-using-chainmap-for-embedded-namespaces/
<p style="color: grey">
Python
recipe 578279
by <a href="/recipes/users/4172944/">Steven D'Aprano</a>
(<a href="/recipes/tags/chainmap/">chainmap</a>, <a href="/recipes/tags/metaclass/">metaclass</a>, <a href="/recipes/tags/namespace/">namespace</a>).
</p>
<p>The Zen of Python tells us:</p>
<p><em>Namespaces are one honking great idea -- let's do more of those!</em></p>
<p>Python already has an excellent namespace type, the module, but the problem with modules is that they have to live in a separate file, and sometimes you want the convenience of a single file while still encapsulating your code into namespaces. That's where classes are the usual solution, but classes need to be instantiated and methods need to be defined with a <code>self</code> parameter.</p>
<p>C++ has "namespaces" for encapsulating related objects and dividing the global scope into sub-scopes. Can we do the same in Python?</p>
<p>With a bit of metaclass trickery and the new ChainMap type from Python 3.3, we can!</p>