On 2006-08-01, Dennis Lee Bieber <[EMAIL PROTECTED]> wrote:
> On Tue, 1 Aug 2006 11:12:31 -0300, Gerhard Fiedler <[EMAIL PROTECTED]>
> declaimed the following in comp.lang.python:
>
>> There's maybe a point in comparing Python variables to C pointers. But it
>> lacks in the respect that a C programmer is used to modify memory locations
>> through pointers. A Python programmer isn't used to modify memory locations
>> in the first place, and simple objects don't get modified at all. There's
>> no Python equivalent to "int*p=345; *p++;". (There's no need for that in
>> Python; I'm not saying this shows a superiority of C. It just shows a
>> different concept of what "variable" means.)
>>
> Python
>
> c = c + 100
>
> pseudo-C (where I use _p to indicate explicit pointer; and all data
> objects are a structure of the form: int ref_count; <object type> data)
>
> scratch_p = malloc()
> scratch_p->data = c_p->data + 100
> scratch_p->ref_count = 1
> c_p->ref_count--
> if !c_p->ref_count
> free(c_p)
> c_p = scratch_p
>
> -------
> b = a
> is
> b = a
> b->ref_count++
>
>
>
>> For me, the point of this discussion was that it makes sense to look at it
>> /differently/. Once you've done that, there's no problem in continuing to
>> use the (vaguely defined) term "variable".
>>
>
> Think the above is "different" enough <G>
The above are implementation details.
Suppose I write a C-interpreter and then would translate a statement
like "c = c + 100" into actions the interpreter would have to take in
order to excute that statement. Something like:
c-addr_p = GetAddress("c");
c-value = *c-addr_p;
sum = c-value + 100;
*c-addr_p = sum;
That look different enough from just "c = c + 100". So maybe C
has no variables either.
--
Antoon Pardon
--
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