I defined a generic TList<IMyInterface> //CORBA style interface

var
    aInt : IMyInterface;
   aObj : TObject;
begin
    aInt :=  MyList.Items[0];
    aObj := aInt as TObject;
   writeln(  IntToHex(LongWord(aInt),4));
   writeln(  IntToHex(LongWord(aObj),4)); //this will output a different
Hex value from previous writeln
//This is causing a problem to me because I later
   MyList.Remove(aObj as IMyInterface);//will fail because it is not the
same as aInt and thus fail to locate the item to remove

Am I missing some fundamental understanding of interface reference?

Dennis

Why do you think the interface and the object are the same ? They are not. An interface is just a bunch of method pointers, and an object has instance data associated with it. Hardly the same thing, I would think ?

Michael.

I think an object and interface are indeed not the same memory and you need to use Supports() to get a reference to the interface from the object. The interface reference can be cached and used later or you need to call Supports every time which does a string compare and is slow.

Regards,
Ryan Joseph

Dennis wrote

Am I missing some fundamental understanding of interface reference?

Bottom line is, NEVER mix Objects and Interfaces. Program for the one or the other.

Regards,
Graeme

2017-05-26 11:08 GMT+02:00 Michael Van Canneyt :

The idea itself is valid, cause "(IMyInterfaceVar as TObject) as IMyInterface = IMyInterfaceVar" is true if and only if IMyInterface is a COM interface. If IMyInterface really is a CORBA interface as Dennis wrote then the compiler should already have complained at the "aObj := aInt as TObject" line as this type of conversion is *not* supported by CORBA interfaces (cause they don't provide QueryInterface() which is needed for this). At least for me the compiler *did* complain (both 3.0.2 and 3.1.1) when I tested this.
So the question is: is IMyInterface indeed a CORBA interface? If so then why does the compiler not complain? If not then why doesn't it work? For both cases a full example would be needed to investigate this.

Regards,
Sven

Sorry, I got it wrong. The interface was in fact COM style instead of CORBA.

In case of COM interface, why

var
    aInt : IMyInterface;
   aObj : TObject;
begin
....
....
...
    aInt := MyList.Items[0];
    aObj := aInt as TObject;

why sometimes (not always) aInt (aObj as IMyInterface ) ?

Dennis

2017-05-27 18:10 GMT+02:00 Dennis Poon :

Would you please provide a full, yet simple as possible example that shows this? I can't reproduce it with merely code fragments as for me it works.

Regards,
Sven