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

[Stefan Behnel]

Chris Angelico, 14.11.2012 14:18:
> On Wed, Nov 14, 2012 at 8:12 PM, Chris Withers wrote:
>> I suspect I'm not the only one who finds:
>>
>> a_dict = dict(
>>     x = 1,
>>     y = 2,
>>     z = 3,
>>     ...
>>     )
>>
>> ...easier to read than:
>>
>> a_dict = {
>>     'x':1,
>>     'y':2,
>>     'z':3,
>>     ...
>>     }
>>
>> What can we do to speed up the former case?
> 
> Perhaps an alternative question: What can be done to make the latter
> less unpalatable? I personally prefer dict literal syntax to a dict
> constructor call, but no doubt there are a number of people who feel
> as you do. In what way(s) do you find the literal syntax less
> readable, and can some simple (and backward-compatible) enhancements
> help that?
> 
> I've seen criticisms (though I don't recall where) of Python,
> comparing it to JavaScript/ECMAScript, that complain of the need to
> quote the keys. IMO this is a worthwhile downside, as it allows you to
> use variables as the keys, rather than requiring (effectively) literal
> strings. But it does make a dict literal that much more "noisy" than
> the constructor.

If that bothers you in a specific case, I recommend using the constructor
instead of a literal.

Stefan