PRE-PROPOSAL: Extension methods (original) (raw)

Rémi Forax forax at univ-mlv.fr
Thu Mar 19 08:10:31 PDT 2009

I vote NO. The problem with extension method is that it doesn't mix well with polymorphism.

Example: interface List { ... }

class Collections { public static void sort(this List<?> list) { // extension methods ... // 1 } }

class SortedList implements List { public void sort() { ... // 2 } }

import static java.util.Collections.*; ... List list=... list.sort(); // call 1

SortedList slist=... slist.sort(); // call 2

List slist2=slist; slist2.sort(); // call 1

The last call is not intuitive in a well known language in which late binding is the default behavior.

Rémi