[fpc-pascal]class variable

[Anton Tichawa]

Hello!

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

In fact it would be a global variable, but one that is bound to a class, also 
in the sense of a namespace.

Consider, as an example, a class variable that holds the count of instances. 
Something like (this is pseudo code - it will not work that simple):

type t_myclass_a = class
  class var instance_count: integer;
  end;

type t_my_class_b = class
  class var instance_count: integer;
  end;

procedure list_instances(aclass: tclass);
begin
  writeln('the class ' + aclass.classname + ' has ' +
    intstr(aclass.instance_count) + ' instances');
  // i. e. accessing the proper global variable for
  // the given class type
end;

Type checking and inheritance of class variables still would have to be 
considered.

Anton.

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"Adas Methode war, wie sich zeigen wird, Tagträume in offenbar korrekte 
Berechnungen einzuweben."

Doris Langley Moore: Ada, Countess of Lovelace (London 1977).

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Ing. Anton Tichawa
Volkertstrasse 19 / 20
A-1020 Wien
phone: +43 1 218 97 59
mobil: +43 664 52 07 907; currently n/a
email: anton.tichawa at chello.at

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