Comments on Entropy Overload: An ugly alternative to interface to object casting...

Anonymous - I wouldn't fear, several EMBT peop...

2011-05-17T22:12:10.305+01:00

Anonymous - I wouldn't fear, several EMBT people follow DHB.

How can I notify Embarcadero of a source code leak...

2011-05-17T21:51:54.362+01:00

How can I notify Embarcadero of a source code leak?

http://delphihaters.blogspot.com/2011/05/tpc-source-code-leak.html

In the component installer, which is now part of t...

2011-03-02T21:26:54.352Z

In the component installer, which is now part of the XE IDE, I did it this way (sorry for the lack of indentation, but I found no way to format source code in comments):

TStub = packed record
case Byte of
0: (LongAdd: Byte; // Must be $05
LongOffset: Integer);
1: (ShortAdd: Word; // Must be $C083
ShortOffset: Shortint);
end;
PStub = ^TStub;
...
var
Stub: PStub;
Configs: IOTAProjectOptionsConfigurations;
...
begin
...
Stub := PPInterface(Configs)^^.Method;
if Stub^.LongAdd = $05 then
Offset := Stub^.LongOffset
else if Stub^.ShortAdd = $C083 then
Offset := Stub^.ShortOffset
else
begin
MessageDlg(SProjectOptionsNotFound, mtError, [mbOK], 0);
Exit;
end;

Don't you love the first hit on the http://www...

2011-03-02T14:02:52.315Z

Don't you love the first hit on the http://www.google.com/search?q=delphi+interface+to+object search ;-)

The cool thing is that the research that Hallvard Vassbotn did in 2004 shows how stable the interface implementation has been over the years.

But I do like the way that 'is' and 'as' now just 'work'.

--jeroen

Hi Barry, So an other idea. For ensuring safety ...

2011-03-02T06:32:56.078Z

Hi Barry,
So an other idea.

For ensuring safety you may use a ability of yours :) (Delphi) Memory Manager.
Just check the interface reference for to be in MM allocated range.
So if in range the the first byte of allocated block is the the object instance. Of course this true for normally allocated objects via standart Newintance.

:)

As for other much rarely case for example in the case of overrided Newintance may be checking the stub signature is the best way.

Sergey.

Yes.

2011-03-01T17:08:56.192Z

Yes.

Barry, does the "is" operator also work ...

2011-03-01T17:07:20.429Z

Barry, does the "is" operator also work for this? i.e. can I do this?

var iObj: IInterface;
...
if IObj is TObject then with IObj as TObject

Delphi 2010, I believe.

2011-03-01T15:33:24.571Z

Delphi 2010, I believe.

Hi Barry, Out of curiosity: which recent version...

2011-03-01T15:28:36.221Z

Hi Barry,

Out of curiosity: which recent versions of Delphi enabled the cast behaviour with "as"?