Hi,

What does it take for a class to access a field using FieldAddress(...)?

I have tried with both typeinfo on/off ({M+}), placing the field in private/protected/public/published
sections but to no avail.

My simple code is:

TMyObject = class
private
   FRef: TMyObject;
   procedure SetRef(AValue: TMyObject);
public
   property Ref: TMyObject read FRef write SetRef;
end;

then i have tried to get the adress in two ways:

AMyObject.FieldAddress('FRef');   //returns nil
AMyObject.FieldAddress('Ref'); //also returns nil

If i run my code through debugger, the VMT FieldTable is empty suggesting no information is
created. This happens in all cases of typeinfo on/off and differenc sections...

What can i do to make the fieldadress accessible?

Regards,
Torsten.

This method return a field address, eg:

{$M+}
  TMyObject = class(TObject)
    FRef: TMyObject;
  end;

...

var
  VMyObject: TMyObject;
  VRef: Pointer;
begin
  VMyObject := TMyObject.Create;
  VRef := VMyObject.FieldAddress('FRef');

If you whant to get a property, use the TypInfo.GetObjectProp function.

So FieldAddress can only access published fields?

Regards,
Torsten.

"Torsten Bonde Christiansen" wrote

So FieldAddress can only access published fields?

Correct. For anything else you'll have to wait till we have Delphi's extended RTTI.

Regards,
Sven