the address of list.append and list.append.__doc__

[Gabriel Genellina]

En Wed, 26 Sep 2007 01:22:37 -0300, HYRY <ruoyu0088 at gmail.com> escribi�:

> I installed python 2.4.4 and tried id(list.append.__doc__) again, here
> is the result, only id(list.append.__doc__) changes, this is strange,
> and only happened in the command line. Because I am doing something
> program that use this id in the command line. Can someone help me try
> this on your PC, I want to know which is the problem: this version of
> python, or my PC.

"the problem"?
Perhaps if you explain what you really want to do, someone can think the  
way to do that, most likely *not* using id()

>>>> id(list.count.__doc__)
> 11863968
>>>> id(list.count.__doc__)
> 11863968
>>>> id(list.count.__doc__)
> 11863968
>>>> id(list.count.__doc__)
> 11863968

This behavior is an accident. The actual doc strings are stored as C  
null-terminated strings inside the C structures defining the list type.  
When you request list.append.__doc__, a Python string object has to be  
built pointing to the original C string. After the call to id(), nobody  
references that string object, and it is garbage collected. Next time you  
request the same thing, depending on the details on how the memory  
allocator works, it may or may not reuse the same memory address. Try with  
some print "hello" in between those id calls.

-- 
Gabriel Genellina