🚀 go-pugleaf

I've posted Ajay Kamdar's proposal to the german DIN-group (most of them
from Siemens Nixdorf Informationssysteme AG) at ISO.
Manfred Lichtmannegger made a good point (new surprises) in his answer:

 To make destructors of a polymorphic class virtual is a cheap strategy
 as a vtbl-pointer already exists. 
 
 But a virtual destructor is only necessary if a non trivial destructor (*)
 in some derived class exists (**). This is totally independent whether the
 class is polymorphic or not (ignoring the virtual destructor itself :-).
 
 The main problem with the proposal is that if you remove the last virtual method,
 the destructor will loose its implicit virtual, independently whether the virtual
 was semantically necessary or not.
 
 I think this side effect would really surprise programmers. Therefore the
 proposal would reduce the frequency of a common programming error by
 introducing a new subtlety. You reintroducing a new area for this common
 programming error, as it is hard ito trace whether the destructor has lost
 its virtuality by changes in direct or indirect base classes.
 
 (*) for instance deleting some pointer members 
 
 (**) this condition is not locally deceidable. Therefore the best would be
      to define every destructor virtual, but in some cases the vtbl-ptr would
      be to expensive.
      
 MfG Manfred Lichtmannegger
 
 --
 "Autobahnen sind elementar auch in der Oberhoheit der Laender"
 Bundeskanzler Kohl zur Zukunft der Datenautobahnen
 
 email: Manfred.Lichtmannegger@mch.sni.de

 [ address and telephone eleded ] 


Ulf Schuenemann

--------------------------------------------------------------------
Ulf Schünemann
Fakultät für Informatik, Technische Universität München, Germany.
email: schuenem@informatik.tu-muenchen.de
WWW:   http://www.informatik.tu-muenchen.de/cgi-bin/nph-gateway/hphalle2/~schuenem/index.html
...there is only one way to "skin a C+@"...:)  -- Jim Fleming