Steam wrapper, exploring options

[Chebmaster]

That instancePtr is puzzling for now. Just pointer.

Consider this:

type 
TMyClass = class
  function MyMethod(): boolean;
end;

But inside MyMethod implementation, you have access to automatically added variables Result and Self. Result is what received the function result while Self is the class instance from which this method was called:

var 
MyInstance: TMyClass;
b: boolean;
...
b:= MyInstance.MyMethod;

..but where does Self come from?
It's not magic, it's not rocket science. Any class method is in fact a regular procedure/function with one hidden "Self" parameter in its parameter list. Both Pascal and C++, could be boiled to

function MyClass_MyMethod(Self: TMyClass): boolean;

Edit: virtual methods are the same it's the process of *calling* them that is more tricky.

In this form you can *export* it from, say, your DLL, C-style. I'm sure *lots* of windows API functions that require you first get a handle to object then pass that handle to various other functions, may very well be constructor and class methods in disguise. Because THandle is ptruint, a pointer-sized unsigned integer.
Things like TMyClass are typed pointers as well.

[Chebmaster]

P.S. A working sample from my GUI code that exploits this:
(inspited by web programming in JavaScript I use for living)

  
  TEventSubscriptionMethodType = (
    esmt_simple, //a method with no parameters
    esmt_string  //a method receiving single UnicodeString
  );  

  TEventSubscription = record
    Receiver: TChepersyObject ;
    Method: AnsiString;
    MethodType: TEventSubscriptionMethodType;
    DefaultString: UnicodeString;
  end; 

function TControl.PassEvent(var ES: TEventSubscription; w: UnicodeString): boolean;
  type tmethod_with_str_par = procedure(slf: TObject; par: UnicodeString);
  var
    method: procedure(slf: TObject);
    rclass: CChepersyObject;
    //method_with_str_par: procedure(slf: TObject; par: ansistring) //#$%@#. It compiles, works, but code completion is shoot >:( absolute method; //har har, two variables accupying the same address Ain't I clever?
    //a hack: calling orbitrary class method by its string name.
    //watch the parameter list! (shall either be none or one ansistring,
    //with ClickReceiverParam either nil or a non-empty string accordingly!)
  begin
    if not Assigned(ES.Receiver) then begin
//...irrelevant to this topic
    end
    else begin
      if w = '' then w:= ES.DefaultString;
      Result:= Yes;
      pointer(method):= ES.Receiver.MethodAddress(ES.Method);
      if not Assigned(pointer(method)) then begin
        AddLog(RuEn(
          'Класс %0: не удалось передать событие, подписчик (%1) не имеет метода "%2" '#13'  параметр: "%3"',
          'Class %0: failed to pass event, the subscriber (%1) doesn''t have a method "%2" '#13'  parameter "%3"'),
            [self.ClassName, ES.Receiver.Classname, ES.Method, w]);
        Exit(No);
      end;
      try
        if ES.MethodType = esmt_simple then method(ES.Receiver)
        else begin
          tmethod_with_str_par(method)(ES.Receiver, w);
        end;
      except
        Die(RuEn(
          'Крах класса %0 при вызове подписчика события, %1.%2(%3)',
          'Class %0 crashed at calling the event subscriber %1.%2(%3)'),
          [self.ClassName, ES.Receiver.Classname, ES.Method, w])
      end;
    end;
  end;