TValue.AsType<T> with enum types in Delphi

Question

Writing this in Delphi

uses System.Classes;
...
var
  A: TAlignment;
  Value: TValue;
begin
  Value := 0;
  A := Value.AsType<TAlignment>();
end;

raises EInvalidCast at AsType.

Is there a way to cast to any enumeration type from an integer value with TValue?

This is of course the obvious answer:

A := TAlignment(Value);

but I wish to provide a generic function that works with other types as well.

Answer 1

This seems to do it:

  if (PTypeInfo(TypeInfo(TAlignment))^.Kind = tkEnumeration) and (Value.TypeInfo.Kind = tkInteger ) then
    case System.TypInfo.GetTypeData(TypeInfo(TAlignment))^.OrdType of
      otUByte, otSByte: PByte(@A)^ := Value.AsInteger;
      otUWord, otSWord: PWord(@A)^ := Value.AsInteger;
      otULong, otSLong: PInteger(@A)^ := Value.AsInteger;
    end
  else
    A := Value.AsType<TAlignment>();

where TAlignment can also be T in a generic function.

(Copied the idea from TRttiEnumerationType.GetValue)