[Python-3000] Change to class construction?

[Phillip J. Eby]

At 07:40 PM 7/9/2007 -0500, Ron Adam wrote:

>Guido van Rossum wrote:
>
>>We could easily change this to return a
>>writable mapping that's not a dict at all but a "view" on the locals
>>just as dict.keys() returns a view on a dict. I don't see why locals()
>>couldn't return the object used to represent the namespace, but I
>>don't see that it couldn't be some view on that object either,
>>depending on the details of the implementation.
>
>This sounds great! I just recently wanted to pass a namespace to 
>exec, but it refuses to accept anything but a dictionary for a local 
>name space.

You can already do that in Python 2.4.


>What I really want to do is pass an object as the local 
>namespace.  And have the exec() use it complete with it's properties 
>intact.  Passing obj.__dict__ doesn't work in this case.

You need a wrapper, e.g.:

      class AttrMap(object):
          def __init__(self, ob):
              self.ob = ob
          def __getitem__(self, key):
              try: return getattr(self.ob, key)
              except AttributeError: raise KeyError, key
          # setitem, delitem, etc...