[Python-Dev] performance of {} versus dict()

Thu Nov 15 00:40:20 CET 2012

On Thu, Nov 15, 2012 at 10:36 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> On 15/11/12 05:54, Mark Adam wrote:
>>> Merging of two dicts is done with dict.update. How do you do it on
>> initialization? This doesn't make sense.
>>> Frequently.
>> my_prefs = dict(default_prefs, setting=True, another_setting=False)
>>> Notice that I'm not merging one dict into another, but merging two dicts
> into a third.

Side point: Wouldn't it be quite logical to support dict addition?
>>> {"a":1}+{"b":2}
Traceback (most recent call last):
 File "<pyshell#59>", line 1, in <module>
 {"a":1}+{"b":2}
TypeError: unsupported operand type(s) for +: 'dict' and 'dict'
It would make sense for this to result in {"a":1,"b":2}.
ChrisA