On 2011-02-26 15:20:19 +0100, David Nadlinger said:
On 2/26/11 1:15 PM, Jonathan M Davis wrote:
[...] And from a perfectly practical standpoint, as soon as your code ends
up in a library, assertions are generally useless anyway,[...]
I don't quite think asserts are useless in libraries. If you need to
care about performance in a library, you hit cases quite frequently
where sanity-checking the input would be too expensive to be done in
release mode, and thus you can't specify behavior on invalid input as
part of your API using exceptions. Nevertheless, it is still useful to
people using your library to get notified when they are messing
something up as early as possible in debug mode, which is precisely
what asserts are made for, at least in my opinion.
But that would only work if they had access to the source, or a version
not compiled in release mode, right?
Hmm.
This is also related to what Jonathan said about programming by
contract -- and only using in-clauses (for example) when you also
control the calling code. I guess what you're saying could be an
argument in the other direction: that even though they certainly
shouldn't be considered part of the public API (beyond documenting what
would be input causing undefined behavior), they *could* be useful in a
library that a client could use in debug mode, because it gives them
some extra tests for their own code, "for free". They can test that
their own code is using your code correctly.
That sounds quite in line with programming by contract to me ... but
then, again, I'm a reall n00b on the subject :)
--
Magnus Lie Hetland
http://hetland.org
