[fpc-pascal]class variable

[Michael Van Canneyt]

On Fri, 4 Apr 2003, Anton Tichawa wrote:

> On Friday 04 April 2003 07:48, you wrote:
> > > Hello!
> > >
> > >>   Can any tell me if there's "Class Variable" in free pascal like in
> > >> java?
> > >>   I mean, in java, you can declare a class memeber to be "static", all
> > >> instance of this class share the same variable memory. Such a member can
> > >> be
> > >> accessed through class name without any instantiation.
> > >>   Does free pascal will add such a feature in the future?
> > >
> > > AFAIK, class variables are not supported yet, nor are class properties.
> > > But
> > > it's possible to use class methods, which in turn access a global
> > > variable.
> >
> > Sorry that is wrong, static class members are supported, you need to
> > enable the static keyword using -St
> >
> > I don't know what you mean with class properties.
>
> Sorry for my misinfo, but I didn't find anything about class variables in the
> docs (1.06), and I tried, in vain, to compile programs with class variables.

I think peter was wrong. He meant class functions or methods.

> I'm happy to learn that -St allows using class variables. It's a pity,
> though, that different keywords have to be used for class variables and class
> methods.
>
> By class properties, I mean properties that only access class members (class
> variables and class methods), and are accessible with the syntax:
>
> <classtype>.<propertyname>.
>
> When trying class methods, I found that the executable behaves strange:
> Invoking a class method with
>
> <classtype>.<method>
>
> works fine. But, invoking the class method with
>
> <classvar>.<method>
>
> is accepted by the compiler, but results in an exception when <classvar> is
> nil. Is that OK?

It depends on what you do in this method. It definitely works, because
e.g. 'Classname' is a class method.

The idea of a class variable is strange to me.
Why not simply use a global variable ?

Michael.