[Python-Dev] PEP 246, redux

Mon Jan 10 18:59:10 CET 2005

At 12:43 PM 1/10/05 -0500, Phillip J. Eby wrote:
>As a practical matter, all of the existing interface systems (Zope, 
>PyProtocols, and even the defunct Twisted implementation) treat interface 
>inheritance as guaranteeing substitutability for the base interface, and 
>do so transitively.

An additional data point, by the way: the Eclipse Java IDE has an 
adaptation system that works very much like PEP 246 does, and it appears 
that in a future release they intend to support automatic adapter 
transitivity, so as to avoid requiring each provider of an interface to 
"provide O(n^2) adapters when writing the nth version of an 
interface." IOW, their current release is transitive only for interface 
inheritance ala Zope or Twisted; their future release will be transitive 
for adapter chains ala PyProtocols.