Re: RFC: Comparable interface

For what it's worth, I'm planning to update the RFC later today with an updated SPL-less patch and the start of a Q&A section similar to what we've had in the other RFCs. I'll send an e-mail when it's ready. On 1 October 2010 04:28, Stas Malyshev <smalyshev@sugarcrm.com> wrote: > It is not clear from the RFC, if the engine encounters $a <= $b, what > actually happens? > E.g.: > 1. Is only $a checked for Comparable or also $b? Both $a and $b are checked. > 2. How it is ensured that if $a < $b then $b > $a? That's up to the userspace developer to get right when they're implementing their compareTo method. I expect the manual would have a dire warning about the possible consequences of not making them equivalent. > 3. Would sorting work with it? Yes. > 4. If both $a and $b are objects with different compare functions, how it is > determined whose function is used? Note that operators like == are assumed > to be commutative, and less/more operators are assumed to be commutative in > pairs, like above. The left operand wins, so $a. > As a side note, if we have traits we might instead think of having > Comparable trait or interface or both, which would declare having > compareTo() standard feature (as Java does) without messing with the engine > and overloading operators. Surely, it would be more verbose, but that might > be a good thing. I don't think that gains us an awful lot (it's no different to simply having an interface or trait within a codebase requiring such a function, which has been common practice in some of the systems I work on anyway), but it'd be easy enough to add, obviously. Adam