How do I instantiate a class from its TRttiType?

Question

I want to create a form given its class name as a string, which has been asked about before, but instead of calling GetClass, I want to use Delphi\'s new RTTI featu

Answer 1

You should use the TRttiContext.FindType() method instead of manually looping through though the TRttiContext.GetTypes() list, eg:

lType := ctx.FindType('ScopeName.UnitName.TFormFormulirPendaftaran');
if lType <> nil then
begin
  ...
end;

But either way, once you have located the TRttiType for the desired class type, you can instantiate it like this:

type
  TFormBaseClass = class of TFormBase;

f := TFormBaseClass(GetTypeData(lType.Handle)^.ClassType).Create(TheDesiredOwnerHere);

Or this, if TFormBase is derived from TForm:

f := TFormClass(GetTypeData(lType.Handle)^.ClassType).Create(TheDesiredOwnerHere);

Or this, if TFormBase is derived from TCustomForm:

f := TCustomFormClass(GetTypeData(lType.Handle)^.ClassType).Create(TheDesiredOwnerHere);

Update: Or, do it like @RRUZ showed. That is more TRttiType-oriented, and doesn't rely on using functions from the older TypInfo unit.