Why am I allowed to do this, why there is no ambiguity complain, and why is the class' method chosen with prior to the other one?
class EX
{
public:
//...
void operator+(const EX& ref)
{
cout << "A";
}
};
void operator+(const EX& ref1, const EX& ref2)
{
cout << "B" << endl;
}
int main()
{
EX obj1{20};
EX obj2{30};
cout << "obj1 + obj2 = " << obj1 + obj2 << endl;
return 0;
}
I was expecting the global function operator+
to be called an "B"
printed on the screen, instead "A"
was printed.
Your member overload accepts only non-const instances of EX
for the first operand while the free overload accepts both const and non-const instances. By overload resolution rules, the non-const wins out because it exactly matches the type being passed in.
You'll get an ambiguity error if you make the member overload const, indicating that *this
is const:
void operator+(const EX& ref) const
{
cout << "A";
}
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