On 30 September 2010 23:13, Gustavo Lopes <glo...@nebm.ist.utl.pt> wrote: > That is, you would only modify zend_std_compare_objects (not > compare_function!) and add there the additional logic where you'd check if > the objects had the same class (or perhaps one was of a subclass of the > other, in which case you'd use the compare method of the subclass) and call > the compare method. > > Allowing comparison of objects with non-objects can become very confusing: > > * What if the objects are not of the same class? What if one is of a > subclass of the other? Is equality not symmetric? > * How do you interact with 'get' and 'cast_object'/'__tostring'?
The initial version of the patch actually did just that: it simply modified zend_std_compare_objects. That's pretty much the cleanest way you could do it. :) I dropped it and went with the more complicated approach involving changing compare_function because I actually think allowing comparison with non-objects is a valuable feature. Objects may be more strongly typed in PHP than scalars, but there's still a certain amount of juggling that can take place via __toString(), so I think it would be out of place to require an object on both sides. Additionally, there are already semantics built into compare_function to handle object/non-object comparisons, although they're of very limited use in practice. The specific use case I had in mind was allowing comparisons of objects representing monetary amounts against numeric values (since that was a particular itch I had a couple of years ago), but I'm sure there would be others. In terms of the specific question as to whether equality is symmetric: certainly it should be, but we would have no way of enforcing it, obviously. Java doesn't either, though: there's simply a note in the documentation saying that implementations should be symmetric. Adam -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
