On Tue, Mar 17, 2009 at 2:14 PM, Chris Rebert <pyideas@rebertia.com> wrote:
On Tue, Mar 17, 2009 at 10:58 AM, Ka-Ping Yee <python@zesty.ca> wrote:
On Tue, 17 Mar 2009, Josiah Carlson wrote:
On Tue, Mar 17, 2009 at 9:03 AM, George Sakkis <george.sakkis@gmail.com> wrote:
On Tue, Mar 17, 2009 at 11:00 AM, Andrii V. Mishkovskyi <mishok13@gmail.com> wrote:
1. Add ability to use '+' operator for dicts
Both of the ideas suffer from "+ is no longer commutative", which sort-of bothers me.
I don't find that a convincing argument, since + is not commutative for lists or tuples either. Andrii's original proposal is the most natural interpretation -- notice that if x and y are dicts:
dict(x.items()) gives x
dict(x.items() + y.items()) gives x + y
That looks perfectly consistent to me.
George's counter-proposal doesn't make sense to me at all -- it messes up the types of all the values in the dict. And it's inconsistent with the built-in behaviour of + with other types: it doesn't add lists element-by-element, so it shouldn't add dicts element-by-element either.
Not to put words into people's mouths, but it seems like the concern was really less over the non-commutativity and move over the fact that data from the first dict gets silently clobbered by the second dict; whereas in the list, tuple, and string cases, no data is ever lost in the process.
Just to be clear, I'm between -0.5 and -1 to the whole idea; my counter-proposal was simply meant to point out the potential ambiguity in semantics and the fact that the original proposal silently loses data. George