On Apr 4, 2015 12:34 AM, "Nikita Popov" <nikita....@gmail.com> wrote: > > On Fri, Apr 3, 2015 at 11:13 PM, Dmitry Stogov <dmi...@zend.com> wrote: >> >> >> >> >> On Fri, Apr 3, 2015 at 11:59 PM, Andrea Faulds <a...@ajf.me> wrote: >>> >>> Hi, >>> >>> > On 3 Apr 2015, at 20:46, Dmitry Stogov <dmi...@zend.com> wrote: >>> > >>> > May be you'll also suggest something regarding bitwise shifts with negative offset? >>> > Allowing negative offsets using opposite directions would fix inconsistency, but I remember, you didn't like it. >>> > May be keep WARNING (Bit shift by negative number) and then perform shift in another direction? >>> > + disable negative shifts at compile-time. >>> >>> I don’t think opposite-direction shifts would work well for a few reasons. I don’t believe this is normal behaviour in other languages, for one. Another issue is that << and >> are not actually opposites, they have different behaviour with respect to signs, so there’d be ambiguity as to what $x << -$y means (is it the same as $x >> $y, or does it deal differently with signs?). Negative shifts being used are usually the result of mistakes, as well, so you want to inform the user. >>> >>> The main problem, though, is that we previously did something different if the shift is negative. Having it now produce a warning, means you’ll see error messages when you run existing code. But shifting in the opposite direction might change the behaviour of existing code silently >>> >>> I think the most sensible solution would be to make negative shifts produce an exception, since they’re really an error, an unsupported operation. I made them be a warning + return FALSE just because it matched division. But that’s not ideal and I’d be fine if it was replaced. >> >> >> OK. Exception is fine. >> >> So the summary: >> >> 1) division by zero produces a warning and +/-INF IS_DOUBLE. Compile-time evaluation is disabled. >> >> 2) Negative shift produces Exception.Compile-time evaluation is disabled. >> >> 3) Modulo by zero produces Exception.Compile-time evaluation is disabled. >> >> Everything right? > > > Don't think we need to disable compile-time evaluation for 2) and 3). It'll just end up being a compile error in that case. I think if you have 1 % 0 occurring in your code literally, it's better to have the compile fail rather than getting (or not getting) a runtime exception.
This is even easier. Andrea, what do you think? Thanks. Dmitry. > > Nikita >
