Experimental Physics and
Industrial Control System

Till Straumann <[email protected]> · Fri, 10 Oct 2008 15:09:08 -0700

Unless I miss something then it seems to me
that EPICS uses 'assert()' in the same way I often
do which AFAIK is incorrect:
assert( expression_with_side_effect );
because if the code is ever compiled with -DNDEBUG then
the side effect (eg locking a mutex in epicsMutexMustLock())
*goes*away*.
'assert' is a macro which evaluates to nothing if NDEBUG is defined.
The correct way of using assert would be:
 result = expression_with_side_effect;
 assert(result);
but it is inconvenient because the message printed by a failed
assertion would only say 'assertion of 'result' failed' and it would
not print the stringified expression.
My guess is that a lot of code would break if ever compiled
with -DNDEBUG...
Again:
#define NDEBUG
epicsMutexMustLock(my_lock);
is a no-op!
FWIW
-- Till

PS: It would be rather useful to have something like
#ifdef NDEBUG
#define usefulEpicsAssert(exp) (exp)
#else
#define usefulEpicsAssert(exp) ((exp) ? (void)(0) : assert(exp))
#endif

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System