Re: A curiosity...

[Keith Thompson <kst-u@mib.org>]

Hyman Rosen <hyrosen@mail.com> writes:
> Randy Brukardt wrote:
>> Every C-language interface that I've every used is
>> full of hacks to get around strong typing.
>> ...
>> Perhaps C programmers are so used to cruft that they
>> fail to abstract it away properly, but that reflects
>> more on the programmers (and the culture that they
>> work it) than the language.
>
> I don't think that's particularly fair, or right.
> The main issue that the sample exposes is that when
> you have a library which needs to accept user objects
> and pass them back into user code, it's going to be
> difficult to define the interface properly without a
> lot of mechanism.
>
> It really is the case that all pthread_create wants
> to do with that pointer is hand it back once it starts
> the thread. I expect that in modern C++, this would
> get wrapped in template code to make sure that the
> type of the pointer passed matches the argument type
> of the thread function, and I guess Ada would use
> generics similarly, but in a C interface, you just do
> the cast and leave it at that.

Except that there's no guarantee in C that converting an int to void*
and back again will yield the original int value.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Nokia
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"