At 10:00 AM 08/12/2002, David Abrahams wrote:
> From: "Philippe A. Bouchard" <philippeb@[...].ca>
> 
> 
> > > I'm not sure if this ptr<> type under discussion works this way, but in
> > > general you can't conformingly use char* arithmetic with offsets to
> find
> > > the sub-parts of non-POD types.
> >
> > The offsets are what static_cast<>s return.
> 
> No, static_cast<> returns pointers, not offsets.
> 
> The standard doesn't guarantee that the offset calculated from a given
> static_cast will work again, given the same source and target types.
> Actually doing the static_cast is the only portable way to find the Base*
> from a Derived*. Indirection through a function pointer which does the
> static_cast might be an option.


This is the kind of code that is trying to fast, rather
than portable, so indirection through a function pointer
would probably be inappropriate.

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