John Gordon wrote: > […] Thomas 'PointedEars' Lahn […] writes:
It is supposed to be an attribution *line*, _not_ an attribution novel. >> >> The obvious way does not work - >> >> >> >> a += (5, 6) >> ^^^^^^ >> > Right, because a tuple is immutable. > >> How did you get that idea? It has been mutated in the very statement >> that you are quoting > > No. An entirely new tuple is created, and 'a' is rebound to it. The > existing tuple is not mutated. Indeed, | $ python3 | Python 3.4.4 (default, Apr 17 2016, 16:02:33) | [GCC 5.3.1 20160409] on linux | Type "help", "copyright", "credits" or "license" for more information. | >>> t = ((1, 2), (3, 4)) | >>> t.__repr__ | <method-wrapper '__repr__' of tuple object at 0x7f4b2ddd2c08> | >>> t += (5, 6), | >>> t.__repr__ | <method-wrapper '__repr__' of tuple object at 0x7f4b2ddca750> indicates that this is so. However, this argument is purely academic, as that rebinding happens would neither validate Ben’s argument nor invalidate mine: The result obtained without the trailing comma is not so “because a tuple is immutable”, but because of how the expression RHS is parsed. -- PointedEars Twitter: @PointedEars2 Please do not cc me. / Bitte keine Kopien per E-Mail. -- https://mail.python.org/mailman/listinfo/python-list
