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copied!<p>Python resolves your variables with -- generally -- three namespaces available. </p> <blockquote> <p>At any time during execution, there are at least three nested scopes whose namespaces are directly accessible: the innermost scope, which is searched first, contains the local names; the namespaces of any enclosing functions, which are searched starting with the nearest enclosing scope; the middle scope, searched next, contains the current module's global names; and the outermost scope (searched last) is the namespace containing built-in names.</p> </blockquote> <p>There are two functions: <code>globals</code> and <code>locals</code> which show you the contents two of these namespaces.</p> <p>Namespaces are created by packages, modules, classes, object construction and functions. There aren't any other flavors of namespaces. </p> <p>In this case, the call to a function named <code>x</code> has to be resolved in the local name space or the global namespace.</p> <p>Local in this case, is the body of the method function <code>Foo.spam</code>.</p> <p>Global is -- well -- global. </p> <p>The rule is to search the nested local spaces created by method functions (and nested function definitions), then search global. That's it.</p> <p>There are no other scopes. The <code>for</code> statement (and other compound statements like <code>if</code> and <code>try</code>) don't create new nested scopes. Only definitions (packages, modules, functions, classes and object instances.)</p> <p>Inside a class definition, the names are part of the class namespace. <code>code2</code>, for instance, must be qualified by the class name. Generally <code>Foo.code2</code>. However, <code>self.code2</code> will also work because Python objects look at the containing class as a fall-back.</p> <p>An object (an instance of a class) has instance variables. These names are in the object's namespace. They must be qualified by the object. (<code>variable.instance</code>.) </p> <p>From within a class method, you have locals and globals. You say <code>self.variable</code> to pick the instance as the namespace. You'll note that <code>self</code> is an argument to every class member function, making it part of the local namespace.</p> <p>See <a href="http://www.network-theory.co.uk/docs/pytut/PythonScopesandNameSpaces.html" rel="nofollow noreferrer">Python Scope Rules</a>, <a href="https://stackoverflow.com/questions/146359/python-scope">Python Scope</a>, <a href="http://showmedo.com/videos/video?name=2800020&fromSeriesID=280" rel="nofollow noreferrer">Variable Scope</a>.</p>

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