How to overload operators with a built-in return type?

Question

Say I have a class, that wraps some mathematic operation. Lets use a toy example

class Test
{
public:
   Test( float f ) : mFloat( f ), mIsInt( false ) {}

   fl         


        

Answer 1

You can't "overload/add" operators for basic types, but you can for your type Type. But this shall not be operator = but operator >> - like in istreams.

class Test
{
public:
   float mFloat;
   int   mInt;
   bool  mIsFloat;
   Test& operator >> (float& v) { if (mIsFloat) v = mFloat; return *this; }
   Test& operator >> (int& v) { if (!mIsFloat) v = mInt; return *this; }
};

Then you can:

int main() {
  float v = 2;
  Test t = { 1.0, 2, false };
  t >> v; // no effect
  t.mIsFloat = true;
  t >> v; // now v is changed
}   

Update

I want to do something like:

updateTime = config["system.updateTime"];

Then with my proposal, you cam:

config["system.updateTime"] >> updateTime;