Re: another emi2 bugfix

--On Tuesday, August 6, 2002 3:13 PM +0300 Oded Arbel <[email protected]> 
wrote:
>> >
>> >> +#define gw_free(ptr) {void *p=ptr;gw_native_free(p);p=NULL;}
>> >
>> > don't you mean :
>> ># define gw_free(ptr) {void *p=ptr;gw_native_free(p);ptr=NULL;}
>> > as p is freed from the stack anyway at the end of the macro block. the
>> > same to  the other change.
>>
>> NO, since 'ptr' can be directly returned from a function and that
>> cannot be made NULL. However, I realise now also that this
>> would not do the trick. It makes the new variable NULL, but not the
>> pointer I wanted.
>>
>> Better drop it for now, and add explicits NULL assignments
>> each time when needed.
>
> Why would you ever want to return a pointer after calling gw_free on it ?
> after freeing a memory segment, the pointer to it must either be set to
> NULL  or discarded.
> doing
> gw_free(pointer);
> return pointer;
> make no sense what so ever, unless gw_free also assigns NULL to the
> pointer.


No, I did not mean that the pointer to be returned from gw_free().
I ment the pointer going INTO gw_free(). That pointer could be returned
from a function. Then you do not have a pointer that can be made
NULL, since it is returned as a value and not a reference to a value.


This is where the pointer can be made NULL:
void *ptr = gw_malloc(1);
gw_free(ptr);
ptr = NULL;

This is where it cannot:
gw_free(gw_malloc(1));

There is no explicit pointer.



Hope this clarifies it,


Harrie

Internet Management Consulting
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