Re: passing args

["DINH V. Hoà" <dinh enserb fr>]

Juergen Boemmels wrote:
> 
> "DINH V. Hoà" <dinh enserb fr> writes:
> 
> > to call the function, you do the following :
> >
> > {
> >    struct struct_arg1_arg2 data;
> >    data->arg1 = arg1;
> >    data->arg2 = arg2;
> >    gtk_timeout_add(interval, function, &data);
> > }
> 
> I'm not sure, but this won't work.
> You alloc the data on the stack, register a pointer to this, add leave
> the function destroying this part of the stack. But it also may even
> work in several cases. Those bugs are realy hard to find.
> 
> When your timeout occurs, you may get a segfault, because the
> stackframe is no longer valid.
> 
> A possible way would be
> {
>   struct struct_arg1_arg2 *data;
> 
>   data = malloc (sizeof (struct struct_arg1_arg2));
>   g_assert (data != 0);
>   /* init data */
>   gtk_timeout_add (interval, function, &data);
> }
> 
> function (struct struct_arg1_arg2 *data)
> {
>   /* do something with data */
>   free (data);
> }

ok, the way I gave won't work but yours won't work too.

because, data will be freed as much as the function is called. (the
function is called periodically with gtk_timeout_add).

then the a better solution is 

 {
   struct struct_arg1_arg2 *data;
 
   data = malloc (sizeof (struct struct_arg1_arg2));
   g_assert (data != 0);
   /* init data */
   gtk_timeout_add (interval, function, &data);
 }
 
 function (struct struct_arg1_arg2 *data)
 {
   /* do something with data */
   // no free
 }


don't forget to free the data at the end of the program or when the
timeout
callback will be stopped.

-- 
Hoa