I am really confused now on how and which method to use to return object from a function. I want some feedback on the solutions for the given requirements.

Scenario A: The returned object is to be stored in a variable which need not be modified during its lifetime. Thus,

const Foo SomeClass::GetFoo() {
 return Foo(); 
}

invoked as:

someMethod() {
 const Foo& l_Foo = someClassPInstance->GetFoo();
//...
}

Scneraio B: The returned object is to be stored in a variable which will be modified during its lifetime. Thus,

void SomeClass::GetFoo(Foo& a_Foo_ref) { a_Foo_ref = Foo(); }

invoked as: someMethod() { Foo l_Foo; someClassPInstance->GetFoo(l_Foo); //... }

I have one question here: Lets say that Foo cannot have a default constructor. Then how would you deal with that in this situation, since we cant write this anymore:

Foo l_Foo

Scenario C: Foo SomeClass::GetFoo() { return Foo(); }

invoked as:

someMethod() {
 Foo l_Foo = someClassPInstance->GetFoo();
//...
}

I think this is not the recommended approach since it would incur constructing extra temporaries.

What do you think ? Also, do you recommend a better way to handle this instead ?