Very Simple C++ Wrapper :: HELP

[Assoul]

Hi Guys,

I know there is a lot to say on Wrapper and there are many threads but I really don't get it as a newbie in C++.

I am trying to use a minimization algorithm called by:

double Calibration::Calibrate() {
...
CSimplex NMS(3,TOL,MAX_ITER,&functionToMinize);
...
}

The thing is functionToMinize is a member function and it has to take only a vector<double> as argument.

So I thought of a Wrapper.

Something like this:

double Wrapper_To_Call_Calibration(vector<double> x)
{
return wrapp -> functionToMinize(x);
}

Obviously this doesn't work. How should I proceed?

Create another class Wrapper with:
attribut Calibration*
constructor that initialize my pointor to my Calibration class.
Then define a function Wrapper_To_Call_Calibration inside this class?

I tried this but it doesn't work.

Any help please? (but very simple help, I am not expert in C++)...

Thanks a lot guys

[D_Drmmr]

Obviously this doesn't work. How should I proceed?

It really depends on the argument type that the CSimplex constructor expects. If it takes a plain function pointer, then you can't get around using global/static data. I.e. you can make functionToMinize a static member function and any data it uses too.

If CSimplex is under your control, I suggest you switch to using a boost::function (or std::function if your compiler supports it) instead of a function pointer. They are much more flexible and can easily be used with member functions.

This code may contain errors, it's only to show the idea.

#include <functional>
#include <vector>
class CSimplex
{
public:
    CSimplex(int, int, int, std::function<double(std::vector<double>)>);
    // ...
};

class Calibration
{
public:
    double functionToMinimize(std::vector<double>);
    double Calibration::Calibrate() {
        CSimplex NMS(3, TOL, MAX_ITER,
            std::bind(&Calibration::functionToMinize, this));
    }
};