Re: [boost] [function] allocator template parameter question

From: Douglas Gregor (doug.gregor_at_[hidden])
Date: 2007-06-07 21:49:02

On Jun 7, 2007, at 2:22 PM, Emil Dotchevski wrote:
> In the implementation I posted, I opted for a parallel line of  
> allocator
> support functions next to the original allocator-less functions. I  
> liked
> this better because no allocator-related stuff is ever instantiated  
> unless
> the user passes an allocator (and most users don't.)

Okay, that makes sense.

> The problem is that most boost::function tests do not use  
> allocators. So
> while the allocator code should work (because it got tested in its  
> original
> form), in it's current form it has only been proven to pass the
> allocator_test.cpp, which is rather simplistic.

Ah.

> To really test everything, one needs to run all tests with the  
> following
> variations:
>
> - pointer to function
> - pointer to member function
> - function object that fits the small object optimization
> - function object that does not fit the small object optimization
> - all of the above variations using an user-supplied allocator.

function_test and function_n_test test most of these, but without the  
user-supplied allocator. You could probably hack up those.

Thanks for implementing this, and so quickly!

Looking briefly through the code... I see that you're not actually  
storing the value of the allocator object itself along with the  
function object. Was that decision intentional, or were you just  
following the behavior of the existing boost::function?

I haven't done a thorough review of the code, but I'd be inclined to  
move boost::function toward this approach. It's a better extension to  
tr1::function than the existing code, and it might be the right way  
for C++0x's "function" to go. If you're interested in this feature  
going into the next standard, I suggest writing a short proposal to  
the C++ Library Working Group for this extension.

        - Doug