On 20/04/2012 03:29 PM, Warp wrote:
> Invisible<voi### [at] devnull>  wrote:
>>> class X; // declaration of X
>
>> Ah, I see. This is the fact I was looking for. :-)
>
>> So this does... what? Tells the compiler "hey, this type exists, but I'm
>> not going to tell you anything about it"?
>
>    It tells that there's a class named X.
>
>    From that point forward you can do anything with that type that does not
> require calling its member functions or accessing its contents. (In other
> words, you can handle pointers and references of that type.) You can also
> make further declarations using it (such as declaring it as the return
> type of a function).
>
>    Doing anything else with an object of that type requires a full class
> definition, but that can be done later in the code.
>
>    This allows inter-dependency between classes.

Right. So I can declare functions that take it or return it, and I can 
declare (but not define) variables of that type. And then I can #include 
the full description before I try implementing anything that actually 
needs to touch it "for real". (?)

>    What I mean is that you can't do this:
>
> class A { B b; };
> class B { A a; };
>
>    That would be a pair of infinitely large classes.

Yes, clearly that can't work.

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