On 09/15/2013 12:10 AM, Francisco Jerez wrote:
> This patch introduces a pair of helper functions providing a common
> implementation of the "new" and "delete" operators for all C++ classes
> that are allocated by ralloc via placement new. The 'ralloc_new'
> helper function takes care of setting up an ralloc destructor callback
> that will call the appropriate destructor before the memory allocated
> to an object is released.
>
> Until now objects needed to call 'ralloc_set_destructor' explicitly
> with a pointer to a static method which in turn called the actual
> destructor in order to get something that should be transparent to
> them. After this patch they'll only need to call 'ralloc_new' from
> the new operator and 'ralloc_delete' from the delete operator, turning
> all overloads of new and delete into one-liners.
I really like the idea of reducing the boilerplate. I'd been meaning to
do that for a while, but was thinking of creating a "rallocable" base
class (which would then introduce multiple inheritance). I never got
around to trying it.
I can't say I'm crazy about this approach, though:
There's still a fair bit of boilerplate; every class still needs to do:
static void* operator new(size_t size, void *ctx)
{
return ralloc_new<whatever>(size, ctx);
}
static void operator delete(void *p)
{
ralloc_delete(p);
}
I'd like to go all the way and condense that to a single line.
This is also the first usage of templates in core Mesa, which I know
will annoy a lot of people. While I would be in favor of using
templates to introduce type safety into things like exec_list or
hash_table, I don't think they provide a very compelling advantage in
this case.
I've sent out a new series which accomplishes the same thing, but
doesn't use templates, and reduces the boilerplate even a bit more.
Comments welcome.
--Ken
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