[BLL] Problem with print vector elements.
Hi, I'm trying to use thew BLL for the first time and I've the following program: class Date { public: Date(long d): _lDate(d) {} long getDate() const { return _lDate; } [...] private: long _lDate; }; std::ostream& operator<<(std::ostream &s, const Date &x) { [...] } struct C { C(long d): date(d) {} Date date; }; int main() { const C c(46000); std::cout << boost::bind(&C::date, boost::lambda::_1)(c) << std::endl; std::vector<C> cont(1, C(46000)); std::for_each(cont.begin(), cont.end(), std::cout << boost::bind(&C::date, boost::lambda::_1)); return 0; } The first std::cout is ok. But for the second one nested int the for_each I get this message error: error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'boost::_bi::bind_t<R,F,L>' (or there is no acceptable conversion) with [ R=const Date &, F=boost::_mfi::dm<Date,C>, L=boost::_bi::list1<boost::arg<1>> ] C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\INCLUDE\ostream(653): could be 'std::basic_ostream<_Elem,_Traits> &std::operator <<<char,std::char_traits<char>>(std::basic_ostream<_Elem,_Traits> &,const char *)' [found using argument-dependent lookup] with [ _Elem=char, _Traits=std::char_traits<char> ] Can you help me? Thank you, Mirko **
On 04/12/2012 11:06 AM, mik wrote:
Hi,
I'm trying to use thew BLL for the first time and I've the following program:
class Date { public: Date(long d): _lDate(d) {} long getDate() const { return _lDate; } [...] private: long _lDate; };
std::ostream& operator<<(std::ostream&s, const Date&x) { [...] }
struct C { C(long d): date(d) {} Date date; };
int main() { const C c(46000); std::cout<< boost::bind(&C::date, boost::lambda::_1)(c)<< std::endl;
std::vector<C> cont(1, C(46000)); std::for_each(cont.begin(), cont.end(), std::cout<< boost::bind(&C::date, boost::lambda::_1));
return 0; }
The first std::cout is ok. But for the second one nested int the for_each I get this message error:
error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'boost::_bi::bind_t<R,F,L>' (or there is no acceptable conversion) with [ R=const Date&, F=boost::_mfi::dm<Date,C>, L=boost::_bi::list1<boost::arg<1>> ] C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\INCLUDE\ostream(653): could be 'std::basic_ostream<_Elem,_Traits> &std::operator <<<char,std::char_traits<char>>(std::basic_ostream<_Elem,_Traits> &,const char *)' [found using argument-dependent lookup] with [ _Elem=char, _Traits=std::char_traits<char> ]
Can you help me?
To be honest, I am surprised that the first cout expression works. Boost.Lambda placeholders don't match well with Boost.Bind. If you meant boost::lambda::bind instead of boost::bind, the for_each should work, assuming you included the header defining the operator overloads for BLL expressions. Assuming that you really meant boost::bind, and instead of ::_1 you accidently wrote boost::lambda::_1, you are in trouble. Boost.Bind only overloads the following operators: !, ==, !=, <, <=, >, >=, &&, ||. Which is the reason your program didn't compile. If you have more problems, please provide a complete testcase (i.e. with includes etc.)
Thank you, Mirko
**
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Hi Thomas, You're right, I've just changed the include from boost/bind.hpp to boost/lambda/bind.hpp and now works perfectly. thank you, Mirko ** On Thu, Apr 12, 2012 at 11:50, Thomas Heller <thom.heller@googlemail.com>wrote:
On 04/12/2012 11:06 AM, mik wrote:
Hi,
I'm trying to use thew BLL for the first time and I've the following program:
class Date { public: Date(long d): _lDate(d) {} long getDate() const { return _lDate; } [...] private: long _lDate; };
std::ostream& operator<<(std::ostream&s, const Date&x) { [...] }
struct C { C(long d): date(d) {} Date date; };
int main() { const C c(46000); std::cout<< boost::bind(&C::date, boost::lambda::_1)(c)<< std::endl;
std::vector<C> cont(1, C(46000)); std::for_each(cont.begin(), cont.end(), std::cout<< boost::bind(&C::date, boost::lambda::_1));
return 0; }
The first std::cout is ok. But for the second one nested int the for_each I get this message error:
error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'boost::_bi::bind_t<R,F,L>' (or there is no acceptable conversion) with [ R=const Date&, F=boost::_mfi::dm<Date,C>, L=boost::_bi::list1<boost::**arg<1>> ] C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\INCLUDE\ostream(653): could be 'std::basic_ostream<_Elem,_**Traits> &std::operator <<<char,std::char_traits<char>**>(std::basic_ostream<_Elem,_**Traits> &,const char *)' [found using argument-dependent lookup] with [ _Elem=char, _Traits=std::char_traits<char> ]
Can you help me?
To be honest, I am surprised that the first cout expression works. Boost.Lambda placeholders don't match well with Boost.Bind. If you meant boost::lambda::bind instead of boost::bind, the for_each should work, assuming you included the header defining the operator overloads for BLL expressions. Assuming that you really meant boost::bind, and instead of ::_1 you accidently wrote boost::lambda::_1, you are in trouble. Boost.Bind only overloads the following operators: !, ==, !=, <, <=, >, >=, &&, ||. Which is the reason your program didn't compile. If you have more problems, please provide a complete testcase (i.e. with includes etc.)
Thank you, Mirko
**
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Thomas Heller