[fpc-pascal]class variable

Anton Tichawa anton.tichawa at chello.at
Fri Apr 4 19:19:18 CEST 2003


> 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;

type t_my_class_b = class
  class var instance_count: integer;

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

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



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

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


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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