by Andrey Tarasevich <andreytarasevich@[EMAIL PROTECTED]
>
Apr 16, 2008 at 04:27 PM
Usenet.9.OkianWarrior@[EMAIL PROTECTED]
wrote:
> I'd like to create a new type which is polymorphic to int but has some
> different characteristics, something like this:
>
> struct ModuloInt : int { // <-- Note: class
> derives from int
> ModuloInt(int Value) : int(Value) {};
> };
>
> int main(void) {
>
> ModuloInt i = 10;
> }
>
> Neither Microsoft C++ 2008 (Express) nor gcc version 4.1 thinks this
> is legal.
Not surprisingly. This is illegal in C++.
> I've looked all over the net, but no one has an example of
> this or explains why this type of inheritance won't work.
It depends on what you mean by "why". Short answer: 'int' is not a class
type and in C++ one can inherit from class types only.
> I can of course make the new class by composition and operator
> overloading, but I always thought that the builtin types were
> considered cl***** in C++.
They have never been considered cl***** in C++.
> Is there a rule somewhere which states that only user-defined cl*****
> can be inherited from?
Only cl***** can be inherited from, which is stated in the language
standard. From the language point of view, all class types are
user-defined.
--
Best regards,
Andrey Tarasevich
