On 8/3/2015 4:57 PM, Steven Schveighoffer wrote:
OK, this brings up another debate. The thing that triggered all this is an issue
with core.time, see issue https://issues.dlang.org/show_bug.cgi?id=14863
Essentially, we wrote code to get all the clock information at startup on a
posix system that supports clock_gettime, which is immutable and can be read
easily at startup. However, how we handled the case where a clock could not be
fetched is to assert(0, "don't support clock " ~ clockname).
The clear expectation was that the message will be printed (along with file/line
number), and we can go fix the issue.
On Linux 2.6.32 - a supported LTS release I guess - one of these clocks is not
supported. This means running a simple "hello world" program crashes at startup
in a segfault, not a nice informative message.
So what is the right answer here?
The answer is the code is misusing asserts to check for environmental errors. I
cannot understand how I consistently fail at explaining this. There have been
many thousand message threads on exactly this topic.
Asserts are for CHECKING FOR PROGRAM BUGS.
enforce(), etc., are for CHECKING FOR INPUT ERRORS. Environmental errors are
input errors, not programming bugs.
