c++ pass data source function as parameter

Question

I have a static function:

void E::createEP(std::list<double>* ret, double length, double (*getHeight)(double)) {
  // magic
  double sampleIntervall = //from magic

  double dist = 0;
  while (length - dist > -0.1) {
    ret->push_back(dist, (*getHeight)(dist));
    dist += sampleIntervall;
  }
}

In different calls I have two different functions to pass as getHeight():

• A function in a database wrapper class which is not static
• A function within the same Object of type E as createEP() (for "recreating" with different parameters), which needs to access Elements fields and can thus not be static, either.

Is it somehow possible to pass non-static functions as parameters to a static function?

If not, what would be the most elegant alternative? I don't want to duplicate the entire code in createEP().

Answer 1

What you can use is a std::function. It will wrap a callable type be that a function, member function, object with an overloaded function operator. You just need to supply the signature to use. So in you case you would have

void E::createEP(std::list<double>* ret, double length, std::function<double(double)> getHeight) 

Then to bind the member function with the object you want to call it on you can use a lambda like

[&](double val){ return object.FunctionName(val); }

or std::bind like

std::bind(&ClassName::FunctionName, &object)