Blast from the past

Wow, look what I just found on an old source-disk. A mini paint program I wrote in Delphi (something) ages ago. It’s all one single component, fully ownerdrawn (notice the scrollbars are not exactly modern) and supports both layers, brushes and undo. Sort of a “bare bone” paint program. I never got around adding filters to it, but you can draw with different effects though. It could be fun to raise it from the dead and give it the pixelrage overhaul.

Blast from the past component

Fun with RTTI

Havent really had time to play with RTTI at all (it’s on my “check it out” list), but today i got inspired by the many cool examples out there and had to give it a go. First stop, dumping an object’s method names. Wish I had this 10 years ago when I made the basic bytecode compiler and 2D game engine GDX. It would have saved me weeks of COM hell.

function getMethodNames(Const aInstance:TObject):TStringList;
var
  mContext: TRttiContext;
  mEntry: TRttiType;
  x: Integer;
  mText:  String;
  mMethods: TArray<TRttiMethod>;
const
  CNT_CLS_PREFIX: Array[Boolean] of string = ('','Class ');
  CNT_MTD_NAME: Array[Boolean] of string = ('function ','procedure ');
begin
  result:=TStringList.Create;
  if aInstance<>NIl then
  begin
    mEntry := mContext.GetType(aInstance.ClassType);
    if mEntry<>NIL then
    Begin
      mMethods:=mEntry.GetMethods;
      for x:=low(mMethods) to high(mMethods) do
      begin
        mtext:=CNT_CLS_PREFIX[mMethods[x].IsClassMethod];
        mText:=mtext + CNT_MTD_NAME[mMethods[x].ReturnType<>NIL];
        mtext:=mText + mMethods[x].Name + '()';
        if mMethods[x].ReturnType<>NIL then
        mText:=mText + ':' + mMethods[x].ReturnType.QualifiedName;
        mtext:=mText + ';';
        result.Append(mText);
      end;
    end;
  end;
end;

Also make sure you checkout some of the more interesting posts about RTTI out there, this article on Delphi sorcery caught my eye, and also this wiki post on Embarcadero’s servers. Attributes is definitively something I have sorely missed from C#. In a couple of weeks I’ll finally have time to read a book again – and will catch up.

This is going to simplify finishing off my tcp/ip remoting system radically. Mapping directly to loaded packages will give better performance than going via exported interfaces. Hm.. (wheels turning)