C++ overload operator '>>'

Question

I have been looking through a lot of different examples and explanations, but none has really answered what I am looking for. I have three classes with a method called connect for each one:

class foo { ... }
void foo::connect(bar br) { ... }

class bar { ... }
bar& bar::connect(baz bz) { ... }

class baz { ... }
baz& baz::connect() { ... }

In my main class, I 'connect' them like this:

foo.connect(bar);
bar.connect(baz);
baz.connect();

or:

foo.connect( bar.connect( baz.connect() ) );

(I know this is briefly explained, I can explain it better if needed)

So, I was trying to overload the operator '>>' to have something like this in the main function:

foo >> bar >> baz;

For the first operator it works, so if I simply do the following, it works fine:

foo >> bar.connect(baz.connect);

But, when I set the other '>>' operator g++ returns this error:

error: no match for ‘operator>>’ in ‘operator>>((* & foo), (* & bar)) >> baz.baz::connect()’

I think I'm not overloading the operator '>>' properly:

bar& operator>> (bar &br, baz &bz)
{
  ...
}

Thanks for the help :)

Answer 1

Operators aren't anything magical: they are just functions spelled in a funny way. That is, your statement

foo >> bar >> baz;

actually just calls [or tries to call]

operator>> (operator>> (foo, bar), baz);

That is, you need the operators

bar& operator>> (foo& f, bar& b) {
    f.connect(b);
    return b;
}
bar& operator>> (bar& b0, baz& b1) {
    return b0.connect(b1);
}

Note, that the last connect() you have won't be doable using operator>>() because the operator always takes two arguments.