On Wednesday, 3 April 2013 at 09:20:02 UTC, Walter Bright wrote:
On 4/2/2013 1:00 PM, Lars T. Kyllingstad wrote:
I definitely don't think we need an IllegalArgumentException.
IMO, passing
illegal arguments is 1) a simple programming error, in which
case it should be
an Error, or 2) something the programmer can not avoid, in
which case it
requires a better description of why things went wrong than
just "illegal
argument". "File not found", for example.
I didn't really consider contracts when I wrote the DIP, and
of course there
will always be the problem of "should this be a contract or a
normal input
check?" The problem with contracts, though, is that they go
away in release
mode, which is certainly not safe if that is your error
handling mechanism.
A bit of philosophy here:
Contracts are not there to validate user input. They are only
there to check for logic bugs in the program itself.
It's a very clear distinction, and should not be a problem.
To reiterate, if a contract fails, that is a BUG in the
program, and the program is then considered to be in an
undefined state and is not recoverable.
CONTRACTS ARE NOT AN ERROR HANDLING MECHANISM.
I completely agree, and this is exactly why we need
InputArgumentError.
Lars
