Re: [boost] Re: Advanced match constants scheme

From: Guillaume Melquiond (gmelquio_at_[hidden])
Date: 2003-06-22 07:08:57

On Sun, 22 Jun 2003, Gennaro Prota wrote:

> On Sun, 22 Jun 2003 00:50:32 +0200 (CEST), Guillaume Melquiond
> wrote:
>
> >We are sure c_l is the nearest 'long double'. Now we want the nearest
> >'double'. Can we simply do:
> >
> >double c_d() { return c_l(); }
> >
> >No, we can't.
>
> We already agreed that a different definition must be provided for
> each type (float, double, long double, and possibly UDTs in some of
> the proposed approaches). Is this the only objection? I haven't
> analyzed the rest of the post because this could be a crucial
> misunderstanding (I've read everything, only a little more
> absent-mindedly).
>
> Genny.

Yes, it's what I meant. A different value should be provided for each type
(and for 'long double', it will have to be machine-dependent: 80, 64+64 or
128 bits) and it must be exactly representable for the type (so, if the
decimal representation of a constant doesn't at least end by a 5, there is
an error). I thought I add to make it clear, since it's not the case in
the "reviewed" library and it will be tedious to implement.

Regards,

Guillaume