Adaptation and typecasting (was Re: [Python-Dev] replacing 'global')

Greg Ewing greg at
Tue Oct 28 20:37:45 EST 2003

"Phillip J. Eby" <pje at>:

> For a protocol p that has immutability as part of its contract,
> adapt(x,p) is well within its rights to return an object that is a
> "copy" of x in some sense.

I don't think that's right -- this should only apply if
the original object x is immutable. Otherwise, changes to
x should be reflected in the view of it provided by p --
even if p itself provides no operations for mutation.

Greg Ewing, Computer Science Dept, +--------------------------------------+
University of Canterbury,	   | A citizen of NewZealandCorp, a	  |
Christchurch, New Zealand	   | wholly-owned subsidiary of USA Inc.  |
greg at	   +--------------------------------------+

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