[Tutor] Accessing calling module's globals in a module

[Roland Schlenker]

Christopher Smith wrote:
> 
> I would like to be able to print a list of variable names and id's in a
> function.  From the documentation I have been able to determine that
> the code below is wrong for 2 reasons:
> 
> >>> def idof2(*v):
> ...  n=globals().keys()
> ...  for vi in v:
> ...   for ni in n:
> ...    if id(ni)==id(vi): print ni,vi
> ...
> >>> idof2(a,b)
> >>>
> 
> 1)  when loaded from a module, globals() only accessess the globals of
> the module not the globals of the module that called the function.
> 
> 2)  the id of the global key (ni above) is not the same thing as the id of
> the object associated with the key.  In writing this I caught the
> second error and replaced the definition with:
> 
> >>> a=2
> >>> b=3
> >>> def id1(*v):
> ...  n=globals()
> ...  for vi in v:
> ...   for nk in n.keys():
> ...    if id(n.get(nk))==id(vi):
> ...     print nk + "'s id = "+str(id(vi))
> ...
> >>> id1(a,b)
> a's id = 14986968
> b's id = 14986920
> 
> HOWEVER, if I put this in a module and try to import it it no longer
> works b/c of problem (1).  I've looked through the (very useful but no
> longer active(?) FAQ) and the documentation.  Can anyone point me
> toward how to access the calling modules global variables?
> 
> Thanks.
> 
> /c
> 
> _______________________________________________
> Tutor maillist  -  Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor

Simply pass your caller's globals to the function.

def id1(callerGlobals, *v):
    for vi in v:
        for k in callerGlobals.keys():
            if id(callerGlobals.get(k)) == id(vi):
                print k + "'s id = " + str(id(vi))

Use as:

id1(globals(), a, b)

I am curious, why do you need to know an objects memory location.

If you want to know if two objects are the same, use the keyword "is".

Python 2.0 (#0, Apr 14 2001, 21:24:22) 
[GCC 2.95.3 20010219 (prerelease)] on linux2
Type "copyright", "credits" or "license" for more information.
>>> a = [1]
>>> b = [1]
>>> a is b
0
>>> c = a
>>> c is a
1
>>> c is b
0
>>> 

Roland Schlenker