[Python-ideas] Empty set, Empty dict

[Victor Stinner]

2014-06-10 8:15 GMT+02:00 Neil Girdhar <mistersheik at gmail.com>:
> I've seen this proposed before, and I personally would love this, but my
> guess is that it breaks too much code for too little gain.
>
> On Wednesday, May 21, 2014 12:33:30 PM UTC-4, Frédéric Legembre wrote:
>>
>>
>>    Now   |  Future  |
>> ----------------------------------------------------
>>    ()    |   ()     |  empty tuple  ( 1, 2, 3 )
>>    []    |   []     |  empty list   [ 1, 2, 3 ]
>>    set() |   {}     |  empty set    { 1, 2, 3 }
>>    {}    |   {:}    |  empty dict   { 1:a, 2:b, 3:c }


Your guess is right. It will break all Python 2 and Python 3 in the world.

Technically, set((1, 2)) is different than {1, 2}: the first creates a
tuple and loads the global name "set" (which can be replaced at
runtime!), whereas the later uses bytecode and only store values
(numbers 1 and 2).

It would be nice to have a syntax for empty set, but {} is a no-no.

Victor