[fpc-pascal]RTTI

[Michael Van Canneyt]

On Mon, 21 Jan 2002, Jean-Pierre PLANAS wrote:

> Hello
>
> Here a piece of delphi code i want to port to fpc.
>
>      uses TypInfo;
>
>      type
> TJour=(jrLundi,jrMardi,jrMercredi,jrJeudi,jrVendredi,jrSamedi,jrDimanche);
>
>      procedure TForm1.btnClick(Sender: TObject);
>      begin
>      ShowMessage(IntToStr(GetEnumValue(TypeInfo(TJour),'jrMardi')));
>      ShowMessage(GetEnumName(TypeInfo(TJour),1));
>      end;
>
> I saw that fpc have a typeInfo.pp unit with GetEnumValue and GetEnumName
> functions.
> But i can use them like with delphi.
>
>      Writeln(GetEnumValue(???(TJour),'jrMardi'));
>      Writeln(GetEnumName(???(TJour),1));
>
> What can replace ??? ?

Version 1.1 contains the TypInfo call.

For version 1.0.x the following workaround can be done;


Type
  {$M+} // VERY Important !!
  TMyEnumClass = Class
    FMyEnym : TJour;
  Published
    property MyEnum : TJour Read GMyEnum Write FMyEnum;
  end;

Now you can do:

Var
  PI : PPropInfo;
  TI : PtypeInfo;

// Store TI in global variable.
begin
PI:=GetPropInfo(TMyEnuMClass,'MyEnum');
If PI<>Nil then
  begin
  TI:=PI^.PropType;
  If TI=Nil then
    begin
    writeln(stderr,'Could not find type information for Myenum');
    Halt(1)
    end;
  end;

The TI can now be used in calls to GetEnumValue:

IntToStr(GetEnumValue(TI,'jrMardi'))
GetEnumName(TI,1);

If you have multiple enumeration types, store them in 1 class, and
repeat the above for each type, storing the PTypeInfo pointers in
variables.

Michael.