Question

I have two methods f(vector<int>& x, ....) and g(DBConn& x, ....)
where the (….) parameters are all identical.

The code inside the two methods are completely identical except for one statement
where we do different actions based on the type of x:

in f(): we do x.push_back(i)
in g(): we do x.DeleteRow(i)

What is the simplest way to extract the common code into one method and yet
have the two different statements?

I am thinking of having a templated functor that overloads operator () (int a) but that seems overkill.

Answer 1

You could write a simple adapter with two implementations, each calling the desired method of a different class.

class MyInterface {
public:
  virtual doIt(int i) = 0;
}

class VectorImp : public MyInterface {
public:
  vector<int>& v;
  VectorImp(vector<int>& theVector) : v(theVector) {}
  doIt(int i) { x.push_back(i); }
}

class DbImp : public MyInterface {
public:
  DBConn& c;
  VectorImp(DBConn& conn) : c(conn) {}
  doIt(int i) { c.DeleteRow(i); }
}