What makes functions special?

[Eric Snow]

On Sat, Jul 9, 2011 at 6:38 PM, Ben Finney <ben+python at benfinney.id.au> wrote:
> Eric Snow <ericsnowcurrently at gmail.com> writes:
>
>> On Sat, Jul 9, 2011 at 4:41 PM, Ben Finney <ben+python at benfinney.id.au> wrote:
>> > Eric Snow <ericsnowcurrently at gmail.com> writes:
>> >> No other objects have code objects. No other objects in Python have
>> >> this special optimization.
>> >
>> > Yes. The two facts are directly related.
> […]
>
>> > Yes, functions are different and are treated differently. What's
>> > your question?
>>
>> My point is that functions are special in Python because they provide
>> a built in optimization via the special execution of code objects.
>
> Functions are special because they define a code object.
>

Right.  But the point is that the code objects (in CPython at least)
allow a special execution of the function body.  What does that
special execution give us?  I am guessing a sufficient performance
increase.  Is there anything else?  And do other Python
implementations do anything special with code objects?

I am not questioning why it was done a certain way, but rather trying
to understand how Python works.

>> I would like to know if it is really that big a deal
>
> Is *what* really that big a deal?
>
> Perhaps this could be clearer if you'd describe what it is that
> surprises you, and how you'd expect it to be different.
>

I don't have any unexpected failure that I ran into or anything like
that.  I am just trying to learn more about the ins and outs of Python
and that tracker issue got me thinking.  And I know that there are
plenty of people on this list that know a lot more about Python than I
do. :)  So I thought I would ask (in my own obscure way) if I was
understanding the definition/execution model correctly.  Sorry for any
confusion.

-eric

>> and if the optimized execution of code objects is a CPython
>> implementation detail or a specification of the language.
>
> I don't know that it's a specification. But functions result in code
> objects, and other statements don't; I am not seeing why treating them
> differently is surprising.
>
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> Ben Finney
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