operator<< overloading

[AvalonX]

Hi forum

Take this example code:

class Object
{
public:

Object(const char *String);

Object &operator<<(const Object &LHS);
}

Object A, B, C, D;

A << B << "test" << C;

What would the last statement be equivalent to?

A)

A.operator<<(B);
Object Temp("test");
A.operator<<(Temp);
A.operator<<(C);

OR

B)

Object Temp("test");
A.operator<<( B.operator<<( Temp.Operator<<( C ) ) );

I believe it is A, but why then do so many tutorials on operator<<-overloading say something like:

"We have to return the [in this case class Object] object, since this allows us to chain multiple objects to be output on a single line (e.g.: A << "blah" << B << C; )."

If the correct equivalent is A, this is wrong, because you don't NEED to return the object for that. You would only have to return it for things like:

if( (A << B << C) == D) return;

Am I right or am I mistaken?

Any help is highly appreciated

[Zaccheus]

It is equivalent to:

A.operator<<(B).operator<<("test").operator<<(C);

Or in other words:

Object& ref1 = A.operator<<(B);
Object& ref2 = ref1.operator<<("test");
Object& ref3 = ref2.operator<<(C);

[treuss]

Neiter A nor B, but

((A.operator<<(B)).operator<<(Object("test"))).Operator<<(C);

So it will run A << B, store the result in a temp and then run temp << Object("test"), and so on.

[laserlight]

If the correct equivalent is A, this is wrong, because you don't NEED to return the object for that.

You should test your hypothesis with an example program where operator<< returns void and yet you attempt operator chaining. After that contrapositive logic will show you that the correct equivalent is not A, as Zaccheus and treuss have noted.

[AvalonX]

Thank you so much to all of you for your responses. You helped me a lot and I understand now why I was mistaken...



Take care.

[code_carnage]

Good that you understood..But I thing I still dont understand is why you have overloaded operator<< in the first place that way.