PEP 245
Scott Finnie
scott at projtech.com
Fri Apr 6 08:16:33 EDT 2001
Hmmm. A question about PEP245: how do interfaces differ from types?
Both seem to have the same motivation: to declare not what something is,
but what it can do:
. "An object's type ... determines the operations that an object
supports (e.g., ``does it have a length?)"
- Python Language reference section 3.1
. "Interfaces try to provide a way for you to ... specify a contractual
obligation for your object"
(PEP245, "The Problem" section).
There are currently limitations on typing (only covers built-ins, object
can only be of a single type) but neither of these seem justifiable
reasons for introducing a new construct rather than extending the
existing one?
- Scott.
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