Re: [Boost-users] [fusion] Adapted struct I/O

Subject: Re: [Boost-users] [fusion] Adapted struct I/O
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2011-11-02 20:41:04

Le 02/11/11 23:56, Mateusz Łoskot a écrit :
> Hi,
>
> I'm still taking early steps with Boost.Fusion.
> I'm trying to adapt a bunch of struct and template struct for easy I/O
> operations.
> I don't understand one thing from the docs. Here we go;
>
> 1) Given the example [1] of template struct adoption:
>
> namespace demo
> {
>      template<typename Name, typename Age>
>      struct employee
>      {
>          Name name;
>          Age age;
>      };
> }
>
> // Any instantiated demo::employee is now a Fusion sequence
> BOOST_FUSION_ADAPT_TPL_STRUCT(
>      (Name)(Age),
>      (demo::employee) (Name)(Age),
>      (Name, name)
>      (Age, age))
>
> [1] http://www.boost.org/doc/libs/1_47_0/libs/fusion/doc/html/fusion/adapted/adapt_tpl_struct.html
>
> 2) The included comment says "demo::employee is now a Fusion sequence".
>
> 3) Jumping to I/O and out docs, reading that [2]
>
> "The I/O operators:<<  and>>  work generically on all Fusion sequences. "
>
> [2] http://www.boost.org/doc/libs/1_47_0/libs/fusion/doc/html/fusion/sequence/operator/i_o.html
>
> 4) Means, I should be able to stream Fusion-adopted demo::employee
>
> #include<iostream>
> #include<string>
> #include<boost/fusion/adapted/struct/adapt_struct.hpp>
> #include<boost/fusion/include/adapt_struct.hpp>
> #include<boost/fusion/sequence/io.hpp>
> #include<boost/fusion/include/io.hpp>
>
> // code from above example goes here
>
> int main()
> {
>      demo::employee<std::string, int>  e;
>      std::cout<<  e<<  std::endl;
> }
>
> 5)  Given what I have learned above, I expect the cout<<  e to work:
>
> $ g++ -I/home/mloskot/dev/boost/_svn/trunk boost_fusion.cpp
> boost_fusion.cpp: In function ‘int main()’:
> boost_fusion.cpp:28:18: error: no match for ‘operator<<’ in ‘std::cout<<  e’
> ...
> I assume complete error is not necessary as my question is of general nature.
>
> Is my expectation valid?
>
Hi,

try adding

#include  <boost/fusion/include/io.hpp>

It is at the end of

[2] http://www.boost.org/doc/libs/1_47_0/libs/fusion/doc/html/fusion/sequence/operator/i_o.html

Best,
Vicente