Re: [boost] Boost MPL metafunction shortcut

Subject: Re: [boost] Boost MPL metafunction shortcut
From: Aleksey Gurtovoy (agurtovoy_at_[hidden])
Date: 2011-04-11 06:20:25

On Sat, 09 Apr 2011 19:36:48 -0500, Agustín Bergé <kaballo86_at_[hidden]>  
wrote:

> On 09/04/2011 16:48, Joel Falcou wrote:
>> I was thinking lately that it is a shame we can't do the following :
>>
>> boost::mpl::transform< SomeSequence, _1&>
>>
>> instead of the lengthy
>>
>> boost::mpl::transform< SomeSequence, add_reference<_1> >
>>
>> same goes for *, const, volatile :
>>
>> boost::mpl::transform< SomeSequence, volatile _1**&>
>>
>
> Some time ago I did some work on a metafunction to perform overload  
> resolution. In the process of emulating and supporting template  
> functions, I ended up with something I like to call 'type patterns' as a  
> byproduct. It allows to query as well as create types based on 'type  
> patterns', as the OP suggest, in a less verbose way. For example:
>
> matches< int( _1, _, _1 ), T >::type
>
> is T a function type returning int, taking three parameters, where the  
> first and the last one are of the same type, and the second one is of  
> any type? If so, which type is _1?
>
> replace< int( _1, _2, _1 ), list< int, float > >::type
>
> create a function type with signature int( int, float, int )
>
> The core of it is a metafunction that decomposes the type declaration  
> into an AST, and applies a visitor function to it. AFAIR, it considered  
> const and volatile modifiers, pointers and references, arrays, pointers  
> to member, function types, and even templates.
>
> Perhaps its time for me to dig such code, and polish it up to boost  
> standards. Would it be interest in adding something like this to MPL?

Most definitely!

-- 
Aleksey Gurtovoy
MetaCommunications Engineering