Delphi - generic type check if is created -


i have following class definition

  tbase<t> = class   public     class var inst: t;     class function getclone: t;   end;

and want check if class var inst assigned.

class function tbase<t>.getclone: t; begin  if tbase<t>.inst = nil //- error here. trying assigned(tbase<t>.inst) nor recognized.     tbase<t>.inst := tbase<t>.create; end;

how can check if class variable assigned?

you need constraint generic parameter in order check nil. example:

tbase<t: class> = class //...

that way t must tobject or descendant of it, can check nil.

without constraint t can integer or other value type doesn't support nil.


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