[RESOLVED] Abstract

[ABuenger]

if a class has a pure-virtual function then is is abstract - and to make this clear to anyone reading the code it is probaly best if you specify this at the class-head (after all the single pure-virtual function that makes the class abstract may be buried several screens down in the class definition).

If someone tries to instantiate my class or derives a class from it without implementing the pure virtual function the compiler gives him an error. And the compiler should only give him the error but not me any warnings.

But a class can be abstract even if there are no pure-virtual functions - all abstract means is that you have to extend this class if you want to uses - a pure virtual function requires this - but there are other circumstances in which it can arise.

If I don't want my class to be instanciated I make the constructor protected. So there is absolutely no need for the abstract keyword.

We gave you the ability to use the 'abstract' keyword instead of '= 0' (and the term' pure virtual function') as abstract is the term that is widely used in OOP for this situation while 'pure virtual function' is a C++-ism.

Google Fight says "pure virtual function" wins over "abstract function" with more than twice as much results ;-)

http://www.googlefight.com/index.php...ct+function%22