[boost] Re: Extensible polymorphic pointer

From: Philippe A. Bouchard (philippeb_at_[hidden])
Date: 2002-08-07 16:02:36

"Philippe A. Bouchard" <philippeb_at_[hidden]> wrote in message
news:airm8o$u3k$1_at_main.gmane.org...
> > More comments:
> >
> > Your code results in undefined behaviour, since it accesses vector
> > elements that have not been constructed.  Even though the data type
> > is POD, accessing vector[i] where i >= vector.size() is not legal C++.
>
> Why is it public then?  There's a flaw in their standards therefore.

If I use resize() instead, will it shrink down the allocated block (exactly
what I don't want) if the new size is smaller than the previous one?

[...]

> > The use of len<> also seems suspect (by which I mean redundant and
> > unnecessary).  It seems that operator+ and operator- should be friend
> > functions of offset.  And the implementation type of offset should
> > probably be ptrdiff_t.  I'm sure there's more oddities lurking, but that
> > should be enough to keep you busy for a while. ;)
> >
> > Dave
>
> len<>() is usefull to implicitly generate offsets, but I'll look at
> ptrdiff_t.

ptrdiff_t is a macro, is therefore not flexible.  offset was created to
simplify pointer arithmetics and to remove some implicit headaches...

Philippe A. Bouchard