[Python-Dev] Opinions on const-correctness?

[David Abrahams]

----- Original Message -----
From: "M.-A. Lemburg" <mal@lemburg.com>


> David Abrahams wrote:
> >
> > > > The largest negative effect I can see is that it'll add some
> > turbulence
> > > > to the CVS log (many little changes).
> > >
> > > -1.
> > >
> > > I've never tried to enforce const-correctness before, but I've
heard
> > > enough horror stories about this.  The problem is that it breaks
3rd
> > > party extensions left and right,
> >
> > Only if you change the strings /returned/ by Python (or structure
> > members) to const char*. Changing your parameters to const char*
won't
> > hurt anybody.
>
> It doesn't hurt already compiled extensions, but it certainly
> breaks *all* yet to be compiled extensions !

Care to explain?

> Besides, it doesn't buy you much, since not all compilers use
> the information for optimization (most I've seen only do careful
> checks of the implied read-only nature which can be very
> annoying).

/No/ conforming compilers use the const-ness of a pointee passed to a
function for optimization, since the pointer can be aliased by a
non-const pointer.

What it buys you, if you're a C++ programmer, is not having to litter
your code with odious casts:

    PyObject_GetAttr(obj, const_cast<char*>("my_attribute"))

-Dave