Paul Ishenin wrote:
David Emerson wrote:
d. What happens with inheritance?
d.1. wrt class constants and class vars-- are there separate
"instances" (for lack of a better word) of these, one instance for
each descendant? Or is the class var/const only stored once for the
ancestor that declares it, and all descendants share that?
Class vars (static class fields) are stored only once for the class
which declares them and all descendants share that.
Example:
TSomeClass = class
class var Value: Integer;
end;
TDescendant = class(TSomeClass);
begin
TSomeClass.Value := 1;
TDescendant.Value := 2;
WriteLn(TSomeClass.Value); // this must output 2
end;
Class static field is not a new feature. But now you can declare them
using 'class var' section after methods or 'type'/'const' section.
Can we have a virtual version too like described here
http://hallvards.blogspot.com/2007/05/hack17-virtual-class-variables-part-i.html
Marc
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