Interfaces without implementation are like a day without sunshine

P T Withington ptw at pobox.com
Thu Aug 24 10:53:29 PDT 2006


What is the rationale for not permitting implementations in  
interfaces?  One of my primary gripes with interface in Java is that  
typically means you are going to have to write the same  
implementations over and over and over, with the risk that one of  
your implementations may skew.

Why not allow implementation in interfaces as a way to package a unit  
of functionality that can be shared by a number of classes?

(There is a good overview of this pattern at http://www.iam.unibe.ch/ 
~scg/Research/Traits/.  Note that the 'traits' here are different  
from the ES4 use of trait in the specification.)



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