Re: [Boost-users] Boost Variant OutputStreamable

From: Ovanes Markarian (om_boost_at_[hidden])
Date: 2006-06-26 03:14:02

Hi!

Can you please to compile this code either with string in the variant or a
vector.

Not sure if it helps but the variant documentation at
http://www.boost.org/doc/html/variant/reference.html states:

namespace boost {
  template<typename T1, typename T2 = unspecified, ..., 
           typename TN = unspecified> 
    class variant;

  template<typename Sequence> class make_variant_over;
  template<typename T1, typename T2, ..., typename TN> 
    void swap(variant<T1, T2, ..., TN> &, variant<T1, T2, ..., TN> &);
  template<typename ElemType, typename Traits, typename T1, typename T2,
..., 
           typename TN> 
    std::basic_ostream<ElemType,Traits> & 
    operator<<(std::basic_ostream<ElemType,Traits> &, 
               const variant<T1, T2, ..., TN> &); }

Which means that the types are not zero-index based. So your T5 would be a
string and not a vector. Make some tests like with simple integers, strings
and finally a vector and see what happens.

Best Regards,
Ovanes

-----Original Message-----
From: Nindi [mailto:Nindi73_at_[hidden]] 
Sent: Sunday, June 25, 2006 15:36
To: boost-users_at_[hidden]
Subject: [Boost-users] Boost Variant OutputStreamable

I have started using Boost recently, and though I should switch my own
variant to the Boost Variant . However I cannot compile the following code

#include<iostream>

#include<vector>

#include<string>

#include<boost/variant.hpp>

std::basic_ostream<char> &operator<<(std::basic_ostream<char>
&theostream,const std::vector<unsigned long> &theVector)

{

for(unsigned long i(0);i<theVector.size();i++)

theostream << theVector[i] << "\n" ;

return theostream;

}

struct TpTemplateVariant {

typedef boost::variant< int,

unsigned long,

double,

bool,

std::string,

std::vector<unsigned long>

> BoostVariant;

};

typedef TpTemplateVariant::BoostVariant Tpvariant;

int main () {

Tpvariant p(5);

std::cout << p;

return 0;

}

The error I get is

error C2679: binary '<<' : no operator found which takes a right-hand
operand of type 'const T5'