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: Joel de Guzman (joel_at_[hidden])
Date: 2010-01-17 21:56:39

On 1/17/2010 10:02 PM, Hicham Mouline wrote:
> Hello,
>
> I have a
> struct params {
> ...
> };
>
> and I have adapted it as a fusion sequence.
>
> However I can't construct a params from a boost::fusion::vector<>  with the same types.
>
> const params p( v );   // v is a fusion::vector with the same type
> const params p = v;   // both failed to compile

Of course you can't, unless your struct params has a template constructor
that accepts fusion sequences -- that's easy enough to do. Keep in mind
that the adapt macro is non-intrusive. What happens in your struct is
your business.

> Do I need to actually write a specific ctor for params?

Yes.

> Will it change the result of the adapt macro?

No.

> Can I iterate with an algorithm over the vector at runtime to assign to p from v?
> with fusion::for_each() I couldn't write the functor that would let me assign to p.

Yep. Perhaps you can use zip_view to iterate both sequences in parallel.
E.g. for_each(zip(p, v), f).

Regards,
-- 
Joel de Guzman
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