[Tutor] Accessing the name of an instance variable - from Edward Comber

[Gregor Lingl]

<forwarded to tutor at python.org>

Hi Gregor. I'm not sure how I should reply. I would have thought I should
reply to the list but this seems to go to you.

This works fine - notice change to globals()

file get_name.py
class A:
    def __init__(self,x,y):
        self.one = x
        self.two = y

    def describe(self):
        print 'Describing'
        this_instance = id(self)
        for name, instance in globals().items(): # vars()
            print name
            if isinstance(instance,A):
                if id(instance) == this_instance:
                        print 'Description of', name
                        print self.one, self.two

if __name__ == '__main__' :

    a = A(1,2)
    b = A(1001,1002)

    a.describe()
    b.describe()


But this won't, from another file presumably because of namespace problems.
I hoped globals() would pick up everything but it doesn't appear to.

import get_name

a = get_name.A(1,2)

a.describe()


Eddie

-----Original Message-----
From: Gregor Lingl [mailto:glingl at aon.at]
Sent: 16 November 2003 11:33
To: Eddie Comber
Subject: Re: [Tutor] Accessing the name of an instance variable




Eddie Comber schrieb:

>For debugging purposes, I would like to be able to print the name of some
>instances of classes directly from the program, together with the class
>data. The data is of course simple but getting the name is a problem to me.
>
>The best I have come up with so far is vars(), from which I can scan for
>instances of the relevant classes.
>
>However the name of the instance is returned as a string. How would I get
my
>hands on the actual instance from this in order to get at its instance so
as
>to print the data? Or is there a better way of going about what I need to
>do?
>
>
Here an example, which uses the built-in function getattr.
Is it this, what you need?

 >>> class A:
        def __init__(self,x,y):
            self.one = x
            self.two = y

 >>> a = A(1,2)
 >>> b = A(1001,1002)
 >>> for name, instance in vars().items():
        if isinstance(instance,A):
            print name, instance.one, instance.two

a 1 2
b 1001 1002
 >>> for name, instance in vars().items():
        if isinstance(instance,A):
            print name
            for var in vars(instance):
                print var, getattr(instance,var)

a
two 2
one 1
b
two 1002
one 1001
 >>>

Regards, Gregor

>Thanks,
>Eddie.
>
>
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