On Monday, 1 January 2018 at 16:47:40 UTC, Adam D. Ruppe wrote:
On Monday, 1 January 2018 at 16:13:37 UTC, Muld wrote:
If you use .ptr then you get zero detection, even in debug
builds.
It is limited to the one expression where you wrote it, instead
of on the ENTIRE program like the build switches do.
It is a lot easier to check correctness in an individual
expression than it is to check the entire program, including
stuff you didn't even realize might have been a problem.
With the .ptr pattern, it is correct by default and you
individually change ones you (should) look carefully at. With
-boundscheck, it is wrong by default and most people don't even
look at it - people suggest it to newbies as an optimization
without mentioning how nasty it is.
It won't be just one line though. When you pretty much have to
use it EVERYWHERE to get the optimization you want. It makes more
sense to just turn off the check for the entire program and use
your own asserts() where they are actually needed. That way you
still get the checks in debug builds and have asserts where they
are actually necessary.
I'd rather there be a potential bug than the program running
to slow to be usable
That's a ridiculous exaggeration. In this program, I saw a < 1%
time difference using those flags. -O -inline make a 50x bigger
difference!
Read the sentence right before this.. Jesus. People only read
what they want.
or have zero debugging for indices in debug builds.
You shouldn't be using .ptr until after you've carefully
checked and debugged the line of code where you are writing it.
That's the beauty of the pattern: it only affects one line of
code, so you can test it before you use it without affecting
the rest of the program.
It won't just be one line, and that's not beautiful. What happens
when code gets refactored? You are constantly going to be
flip-flopping the source code rather than a compiler flag or
using multiple build configurations? How long are you even going
to test for? The error that might happen for the code is probably
difficult to detect, if it wasn't then having bounds checking at
all wouldn't be necessary. Just test your code, that's the beauty
of testing!
