Namespaces

[Dave Angel]

On 01/-10/-28163 02:59 PM, sl33k_ wrote:
> What is namespace? And what is built-in namespace?
>

A namespace is a mapping from names to objects.  When you write a statement
     xyz = 42

the system looks up "xyz" in some namespace and associates that 
"variable" with the object int(42).

The key is that there are multiple namespaces defined.  The built-in 
namespace (containing things such as open, help, next, input, and lots 
more) is always available.  The global namespace, for symbols defined 
globally in the current module, is another namespace.  If you're inside 
a function, there's a separate namespace for symbols defined in there 
(and they behave just a little differently).  And you can explicitly 
specify a namespace with a prefix, which is one way you access symbols 
in another module, or within an instance of an object.

Perhaps look at:
   http://bytebaker.com/2008/07/30/python-namespaces/

though I haven't personally studied the whole thing for accuracy.

One other thing:  dir() can be used to show you the names in a 
particular namespace.  For example,  dir(__builtins__) shows you the 
built-in namespace, while dir() shows you the global one.  And after an 
import, dir() can show you those names:
     import os
     dir(os)

DaveA