"Paul D. Smith" wrote:
>
> %% Ben Laurie <[EMAIL PROTECTED]> writes:
>
> bl> By wrapping them with correctly declared functions.
>
> Are you saying you just don't use const, or that you provide two
> different functions or two interfaces to the same function?
The latter.
> I don't think either of these two options is better than deconstifying
> in this particular commonly-used way. The fact is that C's const is not
> robust enough to handle all these cases, so we have to handle them by
> convention rather than compiler-imposed fiat. This convention is
> well-used and well-understood, and I believe the benefits outweigh the
> problems.
The problem is that people modify something to be const and miss the
fact that it got dropped by a library function, and so modify it. This
is a PITA.
> lhash is a basic library, and if we say you can't store const data in
> lhash (without casting const away first) that's going to have a lot of
> ripple effect.
>
> If I'm missing something maybe you could provide an actual example of
> what you mean, say using the crypto/lhash/lhash.c:lh_insert() function.
In the case of lhash the solution is tedious: provide two versions of
the entire API, one for const data, one not. Whether this is worth the
effort is debatable. Using C++ makes it much easier, of course.
> The problems in BN are much more severe; in my unconst'ing efforts in
> May I went down _exactly_ the same path Richard is going down, and was
> forced to back up and remove all the const'ing I'd done in BN for
> exactly the reasons we are discussing. In this case I agree with Ben
> that const means the function _cannot_, under _any_ circumstances,
> modify the const data. Either the function has to be rewritten to avoid
> that need, or it can't be made const.
Exactly.
Cheers,
Ben.
--
http://www.apache-ssl.org/ben.html
"There is no limit to what a man can do or how far he can go if he
doesn't mind who gets the credit." - Robert Woodruff
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