Re: [Boost-users] [MPL][FUSION] generate fusion::map from mpl::vector

Subject: Re: [Boost-users] [MPL][FUSION] generate fusion::map from mpl::vector
From: Manuel Jung (gzahl_at_[hidden])
Date: 2008-09-29 03:22:48

Adam Merz wrote:

Hey,

> Manuel Jung <gzahl <at> arcor.de> writes:
>> Well this is what i've got so far:
>>
>> template< typename OutSignatures >
>> class filter_impl{
>>         typedef typename mpl::transform< OutSignatures,
>> boost::promise_stream<mpl::_1> >::type OutStreams;
>>
>>         typedef typename mpl::transform< OutSignatures, OutStreams,
>> fusion::make_pair< mpl::_1, mpl::_2 > >::type OutPairs;
>>
>>         typedef typename fusion::result_of::as_map< fusion::vector<
>>         OutPairs >
>> >::type Out_type;
>>
>> }
>> 
>> This compiles fine. But i'm not able to generate some fusion::map from
>> the Out_type.
>> I get compiling errors than.
> 
> Upon looking at your original code further, there does indeed appear to be
> a trivial fix to get it to compile -- add result_of:: before make_pair,
> and get rid of fusion::vector<> around OutPairs:
> 
> 
> template<typename OutSignatures>
> struct filter_impl
> {
>     typedef typename mpl::transform
>     <
>         OutSignatures,
>         boost::promise_stream<mpl::_1>
>     >::type OutStreams;
> 
>     typedef typename mpl::transform
>     <
>         OutSignatures,
>         OutStreams,
>         fusion::result_of::make_pair<mpl::_1, mpl::_2>
>     >::type OutPairs;
> 
>     typedef typename fusion::result_of::as_map<OutPairs>::type OutMap;
> };
> 
> 
> This can now be reduced to the more succinct:
> 
> 
> template<typename OutSignatures>
> struct filter_impl
> {
>     typedef typename fusion::result_of::as_map
>     <
>         typename mpl::transform
>         <
>             OutSignatures,
>             fusion::result_of::make_pair
>             <
>                 mpl::_1,
>                 boost::promise_stream<mpl::_1>
>             >
>         >::type
>     >::type OutMap;
> };

Well this looks nice, but it doesn't compile for me.
I attached the compile errors output.
Thanks!