On Sunday, 28 April 2013 at 13:38:53 UTC, Andrei Alexandrescu
wrote:
[...]
If enough differences accumulate to make bool quite a different
type from a regular integral, then the matter of overloading
with long, conversion from literals 1 and 0 etc. may be
reopened. Even then, it would be a difficult decision.
I agree with most of what you said in your full post, except that
in the quote above you are suggesting that there's a difficult
decision to be made in the case of bool being it's own type
rather than an integral type.
The opposite should be the case, where the decision to keep it as
an integral is a difficult to defend.
I don't see where the difficulty is, because unless bool can
exactly be treated as an integral, then it simply is not an
integral, and unless it is an integral, it cannot be freely
interchanged with the integrals.
The arguments in defense if bool as an integral are IMO weak.
For example, Walter mentioned the case of char successfully being
treated as an integral type rather than a special case "char'
type. However, are there any differences between what char does
and what byte does that interfere with each other? If char
performs exactly like a integral type, then you can convincingly
argue that it is an integral type.
Can the same thing with char be said about bool? No. You can only
say that bool does share some, but not all the characteristics if
an integral.
The other argument in favor boils down to a matter of convenience
under some circumstances. Yes, there are a few cases where it is
advantageous to interchange boolean 'true' and 'false' with
integral 1 and 0, however the vast majority of uses do not rely
on such an interchange, and even if such interchanges are used
often, bool still has significant differences of behavior that
exclude it from being considered as a fully interchangeable
integral type (eg truncation behavior and differences with
operators).
The best you can argue for, is that under some situations, bool
should be freely interchanged with regular integrals, however
that's not going to be true for all cases.
The conclusion ought to be that unless bool can be adjusted into
behaving exactly like all the other integrals, then it simply
cannot be freely interchanged as an integral in all cases, i.e.,
maybe OK in some cases, but certainly not all.
--rt
