Re: [boost] [TTI] Review

Subject: Re: [boost] [TTI] Review
From: Edward Diener (eldiener_at_[hidden])
Date: 2011-07-11 10:27:09

On 7/11/2011 10:12 AM, Joel falcou wrote:
> On 10/07/11 22:59, Edward Diener wrote:
>> I will look into this. It is obviously more difficult programming with
>> the latter than the former, but it is probably doable although with much
>> effort. It may not be worth the effort.
>>
>> What the former syntax reflects is an exact transcription of the
>> template parameters with each comma replaced by ')(' and a starting and
>> ending parentheses. So for the template:
>>
>> 'template <class,class,int,class,template <class> class
>> InnerTemplate,class,long> struct ManyParameters { }'
>>
>> the parameters are:
>>
>> '(class)(class)(int)(class)(template <class> class
>> InnerTemplate)(class)(long)'
>>
>> and all I had to do as an end-user was copy the template parameters, add
>> a '(' at the beginning, add a ')' at the end, and change every ',' to a
>> ')('. As a programmer I take the sequence and directly convert it to the
>> template parameters via a BOOST_PP_SEQ_ENUM.
>>
>
> Dunno if it helps but nt2 has a NT2_STRIP macro adapted from a amcro
> pasoted by Steven Watanabe that conditionnally remove parens around
> symbols.

I already know about this ( Mathias Gaunard reminded me ), and have 
added it to a possible future implementation for pp-lib. The 
implementation needs variadic macro support.

> You can then pass parameters containing comma to the
> preprocessor this way :
>
> FOO( (template<class T, class U> struct foo) )
>
> and this way if no comma is involved
>
> FOO( struct bar )

As long as one has variadic macro support in the compiler this can be 
handled, in which case:

FOO( template<class T, class U> struct foo )

is also possible.

The issue I brought up in my answer to Lorenzo's review remains the 
same: do I drop support for a macro metafunction in TTI if the compiler 
does not have variadic macro support ?