Re: [Boost-users] assignment library with functors

From: François Duranleau (duranlef_at_[hidden])
Date: 2005-12-06 14:37:56

On Tue, 6 Dec 2005, gast128 wrote:

> Dear all,
>
> I am too tired to investigate it deeply, so does anyone know why this does not
> compile (on VS 2003):
>
> typedef boost::function<int (const int& , const int&)> BinOperand;
> typedef std::vector<BinOperand> BinOperandVector;
>
> BinOperandVector operands = boost::assign::list_of(std::plus<int>())
>                                                   (std::minus<int>())
>                                                   (std::multiplies<int>())
>                                                   (std::divides<int>());

That's because the first time you call list_of, it's argument is of type 
std::plus<int>, and this binds the 'assignment object' to that type only. 
Thus all other calls to operator() expects arguments of the same type. The 
solution is to explicitly give the argument type to list_of as BinOperand 
like this:

BinOperandVector operands
      = boost::assign::list_of<BinOperand>(std::plus<int>())
                                          (std::minus<int>())
                                          (std::multiplies<int>())
                                          (std::divides<int>());

-- 
François Duranleau
LIGUM, Université de Montréal
"When there are others, I can perceive myself as an individual. If I am
  alone, then I will be the same as everything else. There will be no
  difference between myself and nothing!"
                                           - from _Neon Genesis Evangelion_