[boost] Re: Interest in smart pointer with value semantics?

From: Thorsten Ottosen (nesotto_at_[hidden])
Date: 2004-01-04 03:03:22

"Dan W." <danw_at_[hidden]> wrote in message
news:bt8glf$3lf$1_at_sea.gmane.org...
> > The most important application of propagating constness is when storing
an
> > object by
> > pointer in a class:
> >
> > class X
> > {
> >     smart_ptr<My_polymorhic_type> p_;
> > public:
> >     int bar() const
> >    {
> >        return p_->this_is_also_a_const_function(); // compile time error
if
> > not
> >     }
> > };
>
> That's neither a const, nor a non-const function of p_, you're calling;
>   it's a function of what p points to.

Please don't obscure the discussion by pointing out language details..

> That a function is const means
> that it doesn't change the class state, i.e.: what _address_ the pointer
> points to. But the target at that address is _not_ part of the state of
> this class,

You cannot make this statement and think it is a universal truth. To me it
is part of the state.
There is nothing to discuss. Some people like it one way, others don't. Both
views should be respected.

>so why should the constness of a member function of _this_
> class have to bear responsibility for some class elsewhere, just because
> we have its pointer?

because the state of the object depends recursively on what member (pointers
or not)
that the object owns.

br

Thorsten