Function attributes

John Posner jjposner at optimum.net
Wed Feb 10 16:08:47 CET 2010


On 2/10/2010 9:36 AM, Steven D'Aprano wrote:
> On Wed, 10 Feb 2010 05:59:41 -0800, Muhammad Alkarouri wrote:
>
>> Hi everyone,
>>
>> What is the simplest way to access the attributes of a function from
>> inside it, other than using its explicit name? In a function like f
>> below:
>>
>> def f(*args):
>>      f.args = args
>>      print args
>>
>> is there any other way?
>
> Not built-in.
>
>
>> I am guessing the next question will be: should I really care? It just
>> feels like there should be a way, but I am not able to verbalise a valid
>> one at the moment, sorry.
>
> I completely agree with you. It is a wart that functions are only able to
> refer to themselves by name, because if the name changes, things break.
> Consider:
>
> old_f = f  # save the old version of the function
>
> def f(x):
>      return old_f(x+1)  # make a new function and call it f
>
> This won't work correctly, because old_f still tries to refer to itself
> under the name "f", and things break very quickly.

They didn't break immediately for me -- what am I missing?:

#-------------------
def f(): return "old func"
g = f
print "name attr of f:", f.__name__
print "name attr of g:", g.__name__

def f(): return "new func"
print "name attr of f:", f.__name__
print "name attr of g:", g.__name__

print "*** calling function currently named f:"
print f()
print "*** calling function currently named g:"
print g()
#-------------------

program output (Python 2.6.4):

name attr of f: f
name attr of g: f
name attr of f: f
name attr of g: f
*** calling function currently named f:
new func
*** calling function currently named g:
old func

-John



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