On 5/3/2010 12:37 AM, Alf P. Steinbach wrote:
* Terry Reedy:
* Alf P. Steinbach:
* Aahz:
and sometimes
they rebind the original target to the same object.
At the Python level that seems to be an undetectable null-operation.
If you try t=(1,2,3); t[1]+=3, if very much matters that a rebind occurs.
Testing:
<test lang="py3">
>>> t = ([], [], [])
>>> t
([], [], [])
>>> t[0] += ["blah"]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>> t
(['blah'], [], [])
>>> _
</test>
Yep, it matters.
So one should instead write t[0].extend('blah') to the same effect, but
without the exception raising assignment attempt, when that is what one
really means ;-).
Terry Jan Reedy
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