Re: [RFC] Comparison and conversion inconsistency - need more info

Hi Stas, On Sun, Nov 10, 2013 at 4:54 PM, Stas Malyshev <smalyshev@sugarcrm.com>wrote: > > I'm wandering whether there are functions like min(). It does not > > I would assume anything that does standard comparisons would be working > the same. Doing otherwise would be, yes, inconsistent. So any function > calling compare_function would do the same thing min() does, I imagine. > > > follow basic comparison/conversion rules. min() behavior is nonsense and > > In which case does min() not follow comparison rules as outlined in the > manual? > http://us2.php.net/min Our manual does not have NULL/BOOL type behavior explanations. > > it would be good fixing min() at some point. Not many users will be > > affected, IMO. > > I think this opinion is wrong, and I don't see why these rules are > "nonsense". Some of these rules may not produce result you have > expected, but only because you are comparing types between which natural > comparison does not exist, so we have to choose some behavior which is > arbitrary to a measure. If you look at Python, for example, "None < -1" > is true (or, if you will, True). In Javascript, however, "null < -1" is > false. Both choices have reasons. > > Changing basic comparison rules in the language has very high potential > of affecting users, since virtually every script does comparisons. Of > course, you don't know if anybody ever compares to nulls, but that's not > impossible, so we need to be very careful. I agree your point fully. I think almost all users are using min() only with integer/float and not with bool/null. The bug report might be confusing, but it's is not complaining -1 != false or like, but it's complaining min() is not following standard PHP comparison rules. ----------------------------------- if (-1 < NULL) echo 'NULL is smaller'; else echo '-1 is smaller'; ----------------------------------- returns '-1 is smaller' as all of us expects. However, ----------------------------------- min(-1,null) ----------------------------------- returns NULL. NULL is evaluated as 0 in scalar contexts, but not with min(). NULL wins negative values because of the compare_function() in zend_operators.c. compare_function() treats NULL/BOOL type special way. (i.e Not like expression in 'if' statement or like) That's the reason why I was surprised. I think feasible solution for min() misbehavior is to use new function that uses standard PHP comparison rule. I'll check PHP functions that uses compare_function() later. There may be other array functions use it. I'm not sure if there are 'internal' functions that does not perform comparison(or conversion) non standard way like compare_function(). It's a small change, but it might have big impact for some users. Therefore, if I'll propose this RFC as PHP 6 matter. Regards, -- Yasuo Ohgaki yohgaki@ohgaki.net