(no subject)

[Alex Martelli]

"sail" <raise_sail at sina.com> wrote in message
news:mailman.1011889136.20179.python-list at python.org...
> hello all,
>    I am  reading the "Python ref-Man" after Tutorial , this is I read it
> second. the first time,  I can not understand it all, but I think I must
read again in future. so Now , I reading. :), have a bit verbosity.
>    I have two questions about function Special attributes:
>
>    1. what is mean of attrib func_dict or __dict__? I defined a function
>   Afunc()  as follow:
>        def Afunc():
> """ A func example"""
> print "Afunc"
>
>   why Afunc.__dict__ is {} ??? I do not know.

Afunc.__dict__ is an empty dictionary because you set no extra, ad-hoc
attributes on object Afunc.  When you do, the dictionary's used:

>>> def Afunc(): print 'Afunc'
...
>>> Afunc.__dict__
{}
>>> Afunc.anattribute = 23
>>> Afunc.__dict__
{'anattribute': 23}
>>>


>    2. like above, I can not know the attrib func_closure. in manual ,
>       this say " free variables", I did not saw it ago at all.

This has to do with "nested scopes".  If a function is nested inside
another, it can access (NOT re-bind) local functions of the functions
it is nested in.  To allow this, the function object must have a
way to find out the one it's directly nested in (if any), and this
is accomplished through the func_closure attribute.

You don't really need to master such stuff to use Python excellently
well, by the way.  The Python Reference manual IS meant for
"language lawyers".  Read the *Library* manual instead, THAT one
is chock full of preciously useful information.


Alex