> On 2007-08-11, Alex Martelli <[EMAIL PROTECTED]> wrote: >> Neil Cerutti <[EMAIL PROTECTED]> wrote: >> ... >>> The Python Language Reference seems a little confused about >>> the terminology. >>> >>> 3.4.7 Emulating numeric types >>> 6.3.1 Augmented assignment statements >>> >>> The former refers to "augmented arithmetic operations", which >>> I think is a nice terminology, since assignment is not >>> necessarily taking place. Then the latter muddies the waters. >> >> Assignment *IS* "necessarily taking place"; if you try the >> augmented assignment on something that DOESN'T support >> assignment, you'll get an exception. Consider: >> >>>>> tup=([],) >>>>> tup[0] += ['zap'] >> Traceback (most recent call last): >> File "<stdin>", line 1, in <module> >> TypeError: 'tuple' object does not support item assignment >> >> Tuples don't support item ASSIGNMENT, and += is an ASSIGNMENT, >> so tuples don't allow a += on any of their items. >> >> If you thought that += wasn't an assignment, this behavior and >> error message would be very problematic; since the language >> reference ISN'T confused and has things quite right, this >> behavior and error message are perfectly consistent and clear. > > Thanks for the correction. I was under the illusion that > sometimes augmented assignment would instead mutate the object.
OK, I've thought about this some more and I think the source of my confusion was I thought assignment in Python meant binding a name to something, not mutating an object. But in the case of augmented assignment, assignment no longer means that? -- Neil Cerutti -- http://mail.python.org/mailman/listinfo/python-list
