Serhiy Storchaka <storchaka+cpyt...@gmail.com> added the comment:
It is how PEP 584 specifies it. The in-place operator is more lenient. It corresponds the behavior of list operators. >>> x = [] >>> y = (1, 2) >>> x + y Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: can only concatenate list (not "tuple") to list >>> x += y >>> x [1, 2] But on other hand, the in-place operator of set is more restrictive: >>> x = set() >>> x |= (1, 2) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unsupported operand type(s) for |=: 'set' and 'tuple' Should not we make "|=" for dict and "+=" for list more restrictive? I heard that it was considered a mistake in list to accept arbitrary iterables. ---------- nosy: +serhiy.storchaka _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue39806> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
