Is there a difference between using a dict literal and a dict constructor?

python dictionary pycharm
maligree picture maligree · Jul 7, 2011 · Viewed 139k times · Source

Using PyCharm, I noticed it offers to convert a dict literal:

d = {
    'one': '1',
    'two': '2',
}

into a dict constructor:

d = dict(one='1', two='2')

Do these different approaches differ in some significant way?

(While writing this question I noticed that using dict() it seems impossible to specify a numeric key .. d = {1: 'one', 2: 'two'} is possible, but, obviously, dict(1='one' ...) is not. Anything else?)

Answer

John La Rooy picture John La Rooy · Jul 7, 2011

I think you have pointed out the most obvious difference. Apart from that,

the first doesn't need to lookup dict which should make it a tiny bit faster

the second looks up dict in locals() and then globals() and the finds the builtin, so you can switch the behaviour by defining a local called dict for example although I can't think of anywhere this would be a good idea apart from maybe when debugging

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