Editing Eiffel (programming language) (section)

===Deferred classes and features===
Classes may be defined with <code>deferred class</code> rather than with <code>class</code> to indicate that the class may not be directly instantiated. Non-instantiatable classes are called [[abstract class]]es in some other object-oriented programming languages. In Eiffel parlance, only an "effective" class can be instantiated (it may be a descendant of a deferred class). A feature can also be deferred by using the <code>deferred</code> keyword in place of a <code>do</code> clause. If a class has any deferred features it must be declared as deferred; however, a class with no deferred features may nonetheless itself be deferred.

Deferred classes play some of the same role as [[interface (object-oriented programming)|interfaces]] in languages such as Java, though many object-oriented programming theorists believe interfaces are themselves largely an answer to Java's lack of multiple inheritance (which Eiffel has).<ref>{{cite web|url=http://www.artima.com/intv/abcs.html |title=Multiple Inheritance and Interfaces |publisher=Artima.com |date=2002-12-16 |access-date=2013-07-08}}</ref><ref>{{cite web|url=https://c2.com/cgi/wiki?MultipleInheritanceIsNotEvil |title=Multiple Inheritance Is Not Evil |publisher=C2.com |date=2007-04-28 |access-date=2013-07-08}}</ref>