Re: GLib queue and stack, alloca discussion

[Havoc Pennington <hp Mcs Net>]

On Fri, 22 Jan 1999, Jeff Garzik wrote:
> 
> should GStack and GQueue be extended to provide analogues to g_list_*
> functions?  ie. I can either provide simple function wrappers that do
> something like
> 
> 	GList * g_queue_nth (GQueue *q, guint position) {
> 		return q ? 0 : g_list_nth (q->list, position);
> 	}
> 
> or have the programmer directly access this by using q->list directly.
> 

IMO this is busted - you can't get the nth thing out of a queue, that's
not how queues work. It's not a queue operation. If you want to do that,
use a list. The queue or stack could also be implemented as an array for
example (in fact that might be nicer if someone wants to do it
eventually), and relying on a listish implementation is busted. 

For precedent, see the STL - a queue or stack is just a vector, but you
can't do vector operations on them. You can't iterate over a stack. 

The whole point of using a queue or stack instead of a list is to place
limits on what you can do with it and thus simplify the code, no? I mean,
it's not like g_list_prepend() is any harder than g_stack_push(). 
The whole point of the wrapper is to make it a stack rather than a list.

Havoc