On Mon, Jul 28, 2014 at 03:33:06PM +0000, dw+python-ideas@hmmz.org wrote:
On Tue, Jul 29, 2014 at 12:59:51AM +1000, Steven D'Aprano wrote:
One good reason is that people are still convinced "dict(A, **B)" makes some kind of sense.
Explain please. dict(A, **B) makes perfect sense to me, and it works perfectly too. It's a normal constructor call, using the same syntax as any other function or method call. Are you suggesting that it does not make sense?
It worked in Python 2, but Python 3 added code to explicitly prevent the kwargs mechanism from being abused by passing non-string keys.
/face-palm Ah of course! You're right, using dict(A, **B) isn't general enough. I'm still inclined to prefer allowing update() to accept multiple arguments: a.update(b, c, d) rather than a += b + c + d which suggests that maybe there ought to be an updated() built-in, Let the bike-shedding begin: should such a thing be spelled ? new_dict = a + b + c + d Pros: + is short to type; subclasses can control the type of new_dict. Cons: dict addition isn't obvious. new_dict = updated(a, b, c, d) Pros: analogous to sort/sorted, reverse/reversed. Cons: another built-in; isn't very general, only applies to Mappings new_dict = a.updated(b, c, d) Pros: only applies to mappings, so it should be a method; subclasses can control the type of the new dict returned. Cons: easily confused with dict.update -- Steven