Using Classes as the KeyType (from the Docs)

[Andrej Mitrovic]

Hi,

There's an example in the docs about classes with a keytype which I don't fully 
understand. Here's the code (taken from 
http://www.digitalmars.com/d/2.0/arrays.html under "Using Classes as the 
KeyType"):

------------------------------------------------------
class Foo
{
    int a, b;

    hash_t toHash() { return a + b; }

    bool opEquals(Object o)
    {   Foo f = cast(Foo) o;
        return f && a == foo.a && b == foo.b;
    }

    int opCmp(Object o)
    {   Foo f = cast(Foo) o;
        if (!f)
            return -1;
        if (a == foo.a)
            return b - foo.b;
        return a - foo.a;
    }
}
------------------------------------------------------


Shouldn't this be written like this instead?:
------------------------------------------------------
class Foo
{
    int a, b;

    hash_t toHash() { return a + b; }

    bool opEquals(Object o)
    {   Foo f = cast(Foo) o;
        return f && a == f.a && b == f.b;
    }

    int opCmp(Object o)
    {   Foo f = cast(Foo) o;
        if (!f)
            return -1;
        if (a == f.a)
            return b - f.b;
        return a - f.a;
    }
}
------------------------------------------------------

Notice I've replaced "foo" with "f"

Foo is the class, but there's no mention of "foo". I'm guessing it was a typo, 
unless I'm missunderstanding something.