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Using Object instead of Class generates compiler error

Posted on 2001-07-19
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Last Modified: 2013-11-23
Hi everyone.

To prevent me from having all the methods of the TObject class while having almost all the advantages of a class, I started to use the Object keyword (to replace Class). Everything worked fine until I started to use them with indexed properties. Doing so forced me to do something like : Result (Object) := MyObject. The problem is that it generates a compiler error with delphi 5 (ex.: error #12345 You should not receive this message...contact Borland...blablabla).

The help files says that Object is supported only for backward compatibility.

 Any clue on why it was leaved, what replaced it and how I can make this work?

GunDamn
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Comment
Question by:comptebidon81
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6 Comments
 
LVL 9

Expert Comment

by:ITugay
ID: 6298290
Hi comptebidon81,

here is small sample. It shows how to create new object, put it into list and then get some it's property by index from the list.

-----
Igor

type
// your object declaration
  PMyObject = ^TMyObject;
  TMyObject = object
  private
    FX: Integer;
    FY: Integer;

    procedure SetX(Value: Integer);
    procedure SetY(Value: Integer);
  public
    property X: Integer read FX write SetX;
    property Y: Integer read FY write SetY;
  end;

// list that keep your objects
  TMyList = class(TList)
  private
    function GetMyObject(I: Integer): TMyObject;
  public
    property MyObjects[Index: Integer]: TMyObject read GetMyObject;
  end;

implementation

procedure TMyObject.SetX(Value: Integer);
begin
  FX := Value;
end;

procedure TMyObject.SetY(Value: Integer);
begin
  FY := Value;
end;

function TMyList.GetMyObject(I: Integer): TMyObject;
begin
  Result := PMyObject(Items[I])^;
end;

.....

var
  L: TMyList;
  M: PMyObject;
begin
  L := TMyList.Create;

  New(M);
  M.X := 128;
  M.Y := 111;
  L.Add(M);

  New(M);
  M.X := 500;
  M.Y := 555;
  L.Add(M);

  Caption := IntToStr(L.MyObjects[0].X);

end;

0
 

Author Comment

by:comptebidon81
ID: 6298486
Thats not bad, but its not what I want.

I already build my Class. It works perfectly except for all the methods that I don't want to see. But I think it is better than having to work with a List. This class will be used by other and I have to make it simple. With my method, the user will have only one object to declare and create.

I don't know if it is possible to do better, but I'd like to try. I would also like to know what happened with "object"

Thanks anyway, Igor
GunDamn
0
 
LVL 9

Expert Comment

by:ITugay
ID: 6298558
Hi comptebidon81,

now I'm living the office, but you can send me the part of your code that doesn't work. I will take a look tomorrow.

-----
Igor.
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Author Comment

by:comptebidon81
ID: 6302887
My code works fine. Its the compiler that has a bug. It stops at the end of a procedure because with the message [Fatal Error] BindingData.pas(1089): Internal error: C10652
This is the line that generates it:
        Result := rMyObject;
were Result and rMyObject are declared with the keyword object (similar to class(Tobject) but with no properties or method)

That is why I wanted to know what happened with this "object" thing.

Thanks again
GunDamn
0
 
LVL 9

Accepted Solution

by:
ITugay earned 75 total points
ID: 6304487
Hi GunDamn,

Ok, seems it's really compiller error. I can't reproduce it, my compiller works fine.
Anyway, it should be no problem to use pure objects.

-----
Igor
0
 

Author Comment

by:comptebidon81
ID: 7469462
It took about a year, but I finnally closed this question!
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