A certainl part of an if() structure never gets executed.

[Nick the Gr33k]

On 15/6/2013 6:53 μμ, Michael Torrie wrote:
> On 06/15/2013 07:07 AM, Nick the Gr33k wrote:
>> result = mylist (since its a no-emoty list)
>>
>>>>>> result.append('bar')
>>>>>> result is mylist
>>> True
>>
>> Never seen the last statement before. What does that mean?
>> result is mylist ????
>
> Yes.  Surprisingling good question.
>
> http://docs.python.org/3.3/reference/expressions.html#is
> http://docs.python.org/3/reference/datamodel.html
>
> One thing that you may find interesting is that what we often call
> variables in Python, and which from your code's point of view look and
> act like variables are in fact names.  Whereas in C, assignment can be
> thought of as copy (a = b in C means that b's value is copied to a), in
> Python assignment is associating a name with an object.  Thus a = b in
> Python means that now the names a and b both are bound (reference to)
> the same object.  That's why the "is" operator is there, to help one
> know if two names point to the same object.
>
> I bring this up on the list from time to time because I find it really
> interesting and intellectually appealing the way Python works.  Hearkens
> back to my class at uni on programming language theory.
>
>

(a = b in C means that b's value is copied to a)

in C:

a = memory chunk able to hold some specific type's value
b = memory chunk able to hold some specific type's value

a = b means

So we have 2 memory units hod, the same value.

in Python:

a and b you say are names, which still are memory chunks

In both situations we still have 2 memory units holding values, so hows 
that different?

-- 
What is now proved was at first only imagined!