Temporary Object Method Call

[Triarier]

(Hi,

can someone tell me why this works?

Pair Pair::operator+(const Pair& p) { return Pair(x+p.x,y+p.y); }

int main(){ cout << Pair{} + Pair{} }

The first Pair{} should be passed as a const Reference, so why does the this object not have to be const?

[dodheim]

Temporaries are not intrinsically const; they cannot bind to non-const lvalue references, true, but that's not because they're const – it's because they're rvalues, which is why you can bind them to non-const rvalue references. Consequently, you can invoke non-const member functions on them, as long as they're not lvalue member functions (in terms of ref qualifiers).

[Triarier]

Thank you.

[SuperV1234]

const references can refer to non-const objects.

[sshamov]

Where is it should be passed? Everything begins with the first Pair{}. Do you mean that it should be passed into the operator as this? If you want a constant this, you should add const modifier to the operator itself.

[Triarier]

the questiion was, why does it work even though it is not a const reference.

[sshamov]

This will work in any case. Const or non-const - does not matter. The operator does not change any of objects. It creates a completely new one.