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Author pitrou
Recipients Joshua.Chin, ethan.furman, pitrou, r.david.murray, rhettinger
Date 2014-10-31.22:23:13
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I think I've changed my mind on this. The important distinction is not between "ducktyping" or "cooperating". It's that this is an in-place mutating operation. A mutating operation should always be the responsibility of the receiver, and so it sounds wrong to be able to delegate it to the read-only operand.

For example, when calling list.extend(op), the list object doesn't allow `op` to take over the operation's semantics. So I think TypeError is the right outcome here.
Date User Action Args
2014-10-31 22:23:13pitrousetrecipients: + pitrou, rhettinger, r.david.murray, ethan.furman, Joshua.Chin
2014-10-31 22:23:13pitrousetmessageid: <>
2014-10-31 22:23:13pitroulinkissue22766 messages
2014-10-31 22:23:13pitroucreate