On May 11, 7:10 am, Steven Watanabe <watanab...@gmail.com> wrote:
since I have access to f I would like to make fsmartenough to handle its own binding. Eg. You'll have to make operator() a template: template<class T> function<double(double)> operator()(const T& x_arg, double y_arg);
Thank you Steven for pointing that out. This is simplest still useful solution I found. I realized that returning function<double(double)> would defeat the purpose since it is not a lambda expression an I would need bind again to insert it in a lambda expression this is the soltution class A{ typedef A this_type; double operator()(double const& x) const{return evaluate(x);} //this is the function that performs the actual work //the following creates a lambda expression using operator() template<class LambdaExp> lambda_functor<lambda_functor_base< action<3, function_action<3> >, tuple< double (this_type::* const)(const double&)const, const this_type, //this class lambda_functor<LambdaExp> const > > > operator()(lambda_functor<LambdaExp> const& exp) const{ return bind( static_cast<double(this_type::*)(double const&) const>(&this_type::operator()), static_cast<this_type const&>(*this), //static_cast not necesary but maybe usefull if CRTP worked exp ); } } it can be used as A a; a(5.); //evaluates at 5. a( _1 + _1) or any lambda expression); //gives a bind lambda expression. as you see the most complicated part is the return type of the function. It can be generalized to functions that take two arguments, if mixed symbolic/numeric evaluation is needed other combinations of can be made or simply using lambda::constant for one or two of the arguments. I tried to use CRTP (e.g. class A: public self_binder<A>{...}) to define the new member in a more generic way but I couldn't because the template member function in a base (parent) class can not be resolved by calling A::operator()(lambda_expr). Maybe as OvermindDL1 said Boost.Phoenix can do better in terms of shorted syntax or by allowing CRTP in some way. Unfortunately I don't know enough Phoenix, maybe Phoenix has a "function" class that is a phoenix-lambda by itself. Thank you, Alfredo