yeah, java also have 2 interface, Comparator and Comparable, which equal to python's compareTo() and __cmp__()
Marc 'BlackJack' Rintsch wrote: > In <[EMAIL PROTECTED]>, Tom Cole wrote: > > > In Java, classes can implement the Comparable interface. This interface > > contains only one method, a compareTo(Object o) method, and it is > > defined to return a value < 0 if the Object is considered less than the > > one being passed as an argument, it returns a value > 0 if considered > > greater than, and 0 if they are considered equal. > > > > The object implementing this interface can use any of the variables > > available to it (AKA address, zip code, longitude, latitude, first > > name, whatever) to return this -1, 0 or 1. This is slightly different > > than what you mention as we don't have to "decorate" the object. These > > are all variables that already exist in the Object, and if fact make it > > what it is. So, of course, there is no need to un-decorate at the end. > > Python has such a mechanism too, the special `__cmp__()` method > has basically the same signature. The problem the decorate, sort, > un-decorate pattern solves is that this object specific compare operations > only use *one* criteria. > > Let's say you have a `Person` object with name, surname, date of birth and > so on. When you have a list of such objects and want to sort them by name > or by date of birth you can't use the `compareTo()` method for both. > > Ciao, > Marc 'BlackJack' Rintsch -- http://mail.python.org/mailman/listinfo/python-list
