On Wed, Dec 10, 2008 at 10:27 PM, Stut <stuttle@xxxxxxxxx> wrote: > On 10 Dec 2008, at 04:15, German Geek wrote: > >> I need to sort an array of objects. I found this ( at a url that didnt let >> me send this msg... ) and I would know how to do it, but I believe there >> might be a cleaner, more elegant way to do it. In Java, you just need to >> implement the interface Comparable and provide a method called compareTo >> (as >> far as i remember) and then you can use one of the many sorting algorithms >> generically on objects that are comparable... >> >> Anyway, I didn't find something like that for PHP. Since I'm using >> symfony, >> I had a bit of a play with the objects at hand and simply did a >> sort($arrayOfObjects) and it did sort them by the id. Just wondering where >> it got the information on what to sort on (not quite) correctly for my >> case? >> > > I'm confused. The function you need is the one you mention in the subject. > All you need to do is create a function that compares two of the objects, in > whatever way you need it to, and returns -1, 0 or 1. The pass that to the > usort function - it doesn't care what type of thing is in the array. Full > details available at http://php.net/usort. I just ment to say it would be nice to have it like in Java or C# where you can implement an interface, called Comparable and define a function in the class called compareTo which returns an integer smaller, equal or greater than 0 by which elements can generically be sorted by in a collection. Since PHP has arrays (hash maps) as the primary collection type, and they are very good for storing sets or other collections, it would be nice to have a sort function that would look, if the elements of the array have a compareTo method (implement the Comparable interface), and if they do, then sort with that. I find it a bit surprising that such a well designed programming language doesn't have such a useful feature. I guess one could use one of the gazillion libraries out there to do the same thing. Also, one could argue that this further checking would slow down functions that are primarily used for sorting strings. However, the answer could be also in the ArrayObject class which is in php natively. Only it should implement all the array functions that are there anyway, which shouldnt be too hard to do for the PHP PL developers. Some more in depth documentation of that class would also be helpful. Anyway, I found a not perfect, but good enough solution: Implement a static compare function in the class of the object and put a function in my library, that is simply called myTools::sort that will get the object class of the first element of the array (if there is one) and sort according to the compare method implemented in that class (if it exists), otherwise just use sort. The compare method takes the parameters as self: public class AClass { // implements Comparable { public static function compare(self $obj1, self $obj2) { return strcmp($obj1->prop1, $obj2->prop1); // e.g. } } That way I will get an exception if there is an object in the array which does not have that class, but i can live with that. At least i'll get an exception and not another funny error, because the parameters are self, right? It might be better to define an interface called Comparable with that method, but was not really necessary for my case. Just a few thoughts to maybe improve PHP in the future. Hopefully there will be a lot of interfaces and objects for collection types at some stage in PHP natively, although that might clutter the namespace and could be realised with libraries. What are your thoughts? -- Tim-Hinnerk Heuer http://www.ihostnz.com
