Re: [Boost-users] [ptr_container] compiler error with BOOST_RESULT_OF_USE_DECLTYPE

Subject: Re: [Boost-users] [ptr_container] compiler error with BOOST_RESULT_OF_USE_DECLTYPE
From: Thorsten Ottosen (thorsten.ottosen_at_[hidden])
Date: 2011-03-03 05:14:15

On 3/3/2011 12:13 AM, Michel MORIN wrote:
> Thorsten Ottosen wrote:
>>> These issues, including OP's one, can be fixed by removing unary function
>>> call
>>> operator of class boost::void_ptr_indirect_fun (i.e. making it
>>> BinaryFunction).
>>
>> The problem then is that we can't use the class with unary functions.
>> Something that might already we be done by users.
>
> So, how about adding void_ptr_indirect_binary_fun (and
> void_ptr_indirect_unary_fun)?
> Then we have
>      void_ptr_indirect_fun (with unary and binary function call operators)
>      void_ptr_indirect_unary_fun (with unary function call operator)
>      void_ptr_indirect_biary_fun (with binary function call operator)
> and use void_ptr_indirect_binary_fun when wrapping comparators.

I was messing around with enable_if to see if we could detect the number 
of arguments. But I couldn't find a traits that does that yesterday ... 
now I see

<boost/function_types/function_arity.hpp>

could help. This way I think we can avoid instantiating result_of until 
it works.

If only we had perfect forwarding and variadic templates, it would be so 
easy to write operator()().

-Thorsten