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How to determine if a property has inherited from a particular class (Views: 100)


Problem/Question/Abstract:

How can I propogate through an object's published properties and extract an actual class reference in order to perform operations like: if GiveProperty is TSomeObjectType then do something?

Answer:

function GetFontProp(anObj: TObject): TFont;
var
  PInfo: PPropInfo;
begin
  {Try to get a pointer to the property information for a
        property with the name 'Font'.
  TObject.ClassInfo returns a pointer to the RTTI table, which we need to pass
  to GetPropInfo}
  PInfo := GetPropInfo(anObj.ClassInfo, 'font');
  Result := nil;
  if PInfo <> nil then
    {found a property with this name, check if it has the correct type}
    if (PInfo^.Proptype^.Kind = tkClass) and
      GetTypeData(PInfo^.Proptype^)^.ClassType.InheritsFrom(TFont) then
      Result := TFont(GetOrdProp(anObj, PInfo));
end;

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