inheritance help

[jab630]

I need to call a function declared like this:

bool addParameterEntry(const string& name, ObjectType& object,
ValueType ObjectType::* object_val_ptr);

and also overloaded like this:

template <class FunctorType, class ValueType>
bool addParameterEntry(const string& name, FunctorType* fctr);

I have been calling it like this:

paramLib.addParameterEntry("Q", problem, &ExpWaveProb::Q);

where ExpWaveProb looks like:

class ExpWaveProb : public WaveProb
{
public:
  double Q;
//...
}

But now that I have made Q a member of WaveProb (and thus ExpWaveProb inherits it), the call above generates the error:

no matching function for call to `LOCA::Parameter::Library::addParameterEntry(const char[2], ExpWaveProb&, double WaveProb::*)'

What would be the easiest way to fix this without changing the addParameterEntry method?

Thanks,
Josh

P.S. Why the functor syntax for a nonstatic field such as Q? I'd have thought to pass it something like &myExpWaveProbReference.Q instead of &ExpWaveProb::Q, so I'm confused.

[Danny]

First of, you can't use quoted literals as template arguments. I won't bore you with the technical explanation why this is illegal but remember that templae type matching rules are very strict, unlike say function overloading resolution. Instead of passing "Q" as the first argument, pass <const string("Q"), ...>
As for the syntax: the :: operator differs from the . operator in one crucial aspect: the former applies to type names (i.e., classes) and namespaces. The latter must take an object instance as the lefthand argument. A pointer to a member function is something that belongs to a class, not an object (you can't define a member function in one object). Of course, when calling that member you call it for a specific instance but the member function's address is fixed and shared by all objects of the same class.