[fpc-pascal] Clone a instance of object

[patspiper]

On 23/09/13 10:02, Michael Van Canneyt wrote:
>
>
> This is wrong. You are typecasting a class reference to an object 
> instance.
>
> The following works:
>
> {$mode objfpc}
>
> Type
>   TBaseObject = class(TObject)
>   public
>   constructor Create; virtual;
>   function Clone:TBaseObject;
>   end;
>   TBaseObjectClass = Class of TBaseObject;
>
> constructor TBaseObject.Create;
>
> begin
> end;
>
> Function TBaseObject.Clone:TBaseObject;
>
> Var
>   C : TBaseObjectClass;
> begin
>   C:=TBaseObjectClass(ClassType);
>   Result:=C.Create;
> end;
What would happen if Result := Self.ClassType.Create were used instead?
>
> Type
>   TMyObject = class(TBaseObject)
>   //   my fields here
>   end;
>
> Var
> o1, o2:TmyObject;
>
> begin
>   o1:=TMyObject.Create;
>   o2 := o1.Clone as TmyObject;
> end.

Stephano