[Python-3000] Discussions with no PEPs

Phillip J. Eby pje at telecommunity.com
Fri Mar 9 00:05:57 CET 2007


At 11:54 AM 3/8/2007 -0800, Bill Janssen wrote:
>I further believe that relying on so-called "duck typing" runtime
>partial information probes is a fragile and error-prone way to build
>software, and that it should be deprecated in favor of "supports this
>interface" tests.

And I believe that "supports this interface" *tests* are equally fragile 
and error-prone -- in a different sort of way.

(I don't have as much reservation about generic functions dispatching based 
on interfaces, because this is overrideable.  Hardcoded interface tests are 
*not* overrideable, and so are far more fragile.)

But we've already had this discussion, I think.  :)



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