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object aware of others

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  object aware of others Lee Chaplin <lchaplin13@gmail.com> - 2012-01-29 16:48 +1300
    Re: object aware of others Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-01-29 04:13 +0000

#19565 — object aware of others

Hi all,

I am trying to create an object that is aware of other objects created
before itself, and when found, then copy some attributes from them,
something like:

class A:
    def __init__(self):
        self.myname = "IamA"
        print 'This is A'
    def foo(self):
        print "foo"
    def update(self):
        i = ''
        obj = self
        for i in globals():
            obj = globals()[i]
            if hasattr(obj, 'myname'):
                print "The only friends I've got are ", i, obj.myname
            else:
                print "Oops, not my friend."


class B:
    def __init__(self):
        print 'This is B'
    def foo(self):
        print "bar"

# a = A()
# b = B()
# c = A()
# c.update()

The last four lines work if they are in the same module as the class
definitions (a000), but it doesn't work if they are called from a
different module, say:

import a000

a = a000.A()
b = a000.B()
c = a000.A()
c.update()

I presume there is something that need to replace the globals() call,
but I cannot find what.
Any help is greatly appreciated.

Thanks,
Lee

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#19567

On Sun, 29 Jan 2012 16:48:34 +1300, Lee Chaplin wrote:

[...]
> The last four lines work if they are in the same module as the class
> definitions (a000), but it doesn't work if they are called from a
> different module, say:

globals() is not actually global to the entire Python session. It 
actually means global to a module. Every module has its own globals().

Python doesn't really have a concept of "global to the entire session" as 
such, although the built-ins comes close. But if you mess with built-ins, 
people will be sarcastic at you. They may even use irony.

However, you can fetch another module's globals by using:

vars(module)


-- 
Steven

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