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Date: Tue, 11 Mar 2014 23:32:53 -0700
From: Ethan Furman <ethan@stoneleaf.us>
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Subject: Re: Tuples and immutability
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Xref: csiph.com comp.lang.python:68261

On 03/11/2014 08:25 PM, Terry Reedy wrote:
> On 3/11/2014 10:01 PM, Rick Johnson wrote:
>>
>> On Thursday, February 27, 2014 4:18:01 PM UTC-6, Ian wrote:
>>> x += y is meant to be equivalent, except possibly in-place and
>>> more efficient, than x = x + y.
>
> The manual actually says "An augmented assignment expression like x += 1 can be rewritten as x = x + 1 to achieve a
> similar, but not exactly equal effect. In the augmented version, x is only evaluated once. Also, when possible, the
> actual operation is performed in-place, meaning that rather than creating a new object and assigning that to the target,
> the old object is modified instead.

... and reassigned to the target.  :)  (If it doesn't say that last part, it should.)

--
~Ethan~