Re: [boost] [function_types]

From: Steven Watanabe (steven_at_[hidden])
Date: 2006-11-28 18:57:03

AMDG

Tobias Schwinger wrote:

> Actually,
>
>     function_type< int(...), tag<components<int(...)>, stdcall_cc> 
> >::type
>
> is equivalent and doesn't read too bad, does it?
>   
I was concerned more about the duplication of int(...).
here is a contrived example.
template<class M, class V, class I>
struct get_function :
 function_type<
   typename mpl::at<M, typename mpl::at<V, I>::type>::type,
   tag<
     components<
       typename mpl::at<M, typename mpl::at<V, I>::type>::type
     >,
     default_cc
   >
 > {};

Of course a simple template could fix this:
template<class F, class Tag>
struct mutate_function :
 function_type<F, tag<mpl::if_<is_callable_builtin<F>, components<F>, 
F>::type, Tag> > {};

>  
>>
>> > > How often are the cv tags likely to be used? They are redundant
>> > since for member functions this information is already available
>> > in the first parameter.  If they are not a very common thing to
>> > need, I would propose simply removing them from the interface.
>>     
> It might not be wise to throw out that feature. Currently cv-qualified 
> function types are illegal, but it is likely they will be allowed in 
> some contexts in the future (there is a defect report on that part of 
> the standard). 
shouldn't that be handled by add_const/is_const?
> Further, these tags might come handy to work around BCC deficiencies.
I hope that would be an implementation detail.

In Christ,
Steven Watanabe