On Fri, Sep 25, 2020 at 6:05 AM Ricky Teachey <ricky@teachey.org> wrote:
I'd like to hear more about why the empty tuple has been selected as the default index.
It makes sense to me: if more than one index is passed, they are passed as a tuple. so many classes need to handle tuples anyway. What other options are there? I suppose None is a possibility, but None is a valid dict key, so probably not a great idea. Hmm, so is an empty tuple. Darn. I think having no default is a better option, as someone pointed out already in this thread. -CHB
On Fri, Sep 25, 2020, 1:07 AM David Mertz <mertz@gnosis.cx> wrote:
Is this a breaking change? It feels borderline.
Keyword-only subscripts are permitted. The positional index will be the
empty tuple: obj[spam=1, eggs=2] # calls type(obj).__getitem__(obj, (), spam=1, eggs=2)
I.e. consider:
d = dict() d[()] = "foo" d {(): 'foo'}
I don't really object to this fact, and one could argue it's not a breaking change since a built-in dict will simply raise an exception with keyword arguments. However, it does make the empty tuple the "default key" for new objects that will accept keyword indices.
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