Re: [Boost-users] fusion struct adapt macro, construct the struct from a fusion vector

Subject: Re: [Boost-users] fusion struct adapt macro, construct the struct from a fusion vector
From: Hicham Mouline (hicham_at_[hidden])
Date: 2010-01-19 13:05:58

----- Original Message ----- 
From: "Hicham Mouline" <hicham_at_[hidden]>
To: <boost-users_at_[hidden]>
Sent: Tuesday, January 19, 2010 4:22 PM
Subject: Re: [Boost-users] fusion struct adapt macro,construct the struct 
from a fusion vector
>> What about:
>>
>>  template <typename Seq>
>>  params(Seq const& seq,
>>    typename boost::enable_if<
>>        fusion::traits::is_sequence<Seq>
>>    >::type* = NULL);
>>
>> ?
>
> Fantastic.
>
> Here is the code I have (plz see below), but it seems there are issues 
> with const-ness that I don't understand.

Following my previous attempt, replacing the functor applied by foreach to 
the zipped sequence by:

struct assignelt {

  template <typename T>
  void operator()( const vector2<const T&, const T&>& seqpairs ) const
  {
    typedef vector2<const T&, const T&> pair_t;
    const_cast<T&>(at_c<0, const pair_t>(seqpairs)) = at_c<1, const 
pair_t>(seqpairs);
  }
};
works.

I can now construct my struct params from an equivalent fusion sequence.
This constructor is identical for all my params struct.
I have structs params1 to params100

Is there a way to factorise this ctor and not repeat its definition in the 
100 struct params?
Is this possible with a base struct templated on the derived struct?

rds,