On 2007-10-05, Lawrence D'Oliveiro <[EMAIL PROTECTED]> wrote:
> In message <[EMAIL PROTECTED]>, Neil Cerutti wrote:
>
>> On 2007-10-03, Lawrence D'Oliveiro <[EMAIL PROTECTED]>
>> wrote:
>>> In Python, all names _are_ variables. They are not "bound" to
>>> objects. The value of os.path is a pointer. It's implemented
>>> as a pointer, it has all the semantics of a pointer.
>>
>> No. A pointer is also an iterator.
>>
>> void duplicate(char *d, const char *s)
>> {
>> while (*d++ = *s++)
>> ;
>> }
>
> So if you can't do pointer arithmetic, then it's not a pointer?
> Trying this:
>
> void duplicate(void *d, const void *s)
> {
> while (*d++ = *s++)
> ;
> }
>
> I get:
>
> test.c: In function 'duplicate':
> test.c:3: warning: dereferencing 'void *' pointer
> test.c:3: warning: dereferencing 'void *' pointer
> test.c:3: error: invalid use of void expression
>
> So you can't do arithmetic or iterate with a void * pointer.
...or dereference.
> Does that mean it's not really a pointer?
That's an interesting taxonimical conundrum. If a pointer were
defined by it's semantics, then yes, a void pointer wouldn't be a
pointer. But pointers are defined not by behavior, but by an
ANSI/ISO standard. The term "pointer to void" makes sense if you
think of it as a pointer in an altered, intermediate state.
I suppose you might score a Pyrrhic victory by claiming that
Python identifiers are pointers that don't behave like pointers.
But you claimed the opposite.
--
Neil Cerutti
--
http://mail.python.org/mailman/listinfo/python-list
