Re: assertions: does it matter that they are disabled in production?
on Mon Aug 04 2008, marlow.andrew-AT-googlemail.com wrote:
Assertions via assert.h (or cassert) are disabled in production and
have to be enabled via the NDEBUG macro. This is one reason I don't
use the assert macro. I always throw an exception that means a fatal
programming error has occurred. Am I the only one that does this?
Surely not. My reasoning is that I always want the checks on, just in
case. This means it is something I tend to do sparingly, after all,
loads of them might well create a performance issue.
All the std programming text tell us how good it is to use assertions
(I am thinking of books like OOSC(II)) but the mechanism they describe
is like cassert every time, i.e turned off in production. I have
noticed that it is hardly ever used on any C++ projects I have seen.
It doesn't seem to get much use in C libraries either but does seem to
have a slightly higher usage there.
Does this mean C++ programmers don't like such a C-like mechanism? Or
they don't don't like the fact that the assertions are disabled in
production? Or is there some other reason?
I'm not sure why you've experienced that. From Boost's point-of-view,
since we are writing libraries, we don't know the precise requirements
of our clients, so we use a typical wrapper (BOOST_ASSERT) whose
behavior on failure can be customized.
However, I wanted to note one point that is typically overlooked in
favor of asserts that disappear in production: a programmer who knows
that an assert will not disappear may be less inclined to write one (for
performance reasons). In many programming scenarios, it's a good idea to
encourage *lots* of assertions.
--
Dave Abrahams
BoostPro Computing
http://www.boostpro.com
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