On 2 March 2017 at 09:36, M.-A. Lemburg <m...@egenix.com> wrote: > On 02.03.2017 09:03, Serhiy Storchaka wrote: > > Function implemented in Python can have optional parameters with default > [...] > Why a new syntax ? Can't we just have a pre-defined sentinel > singleton NoDefault and use that throughout the code (and also > special case it in argument parsing/handling)? >
I think for the sane reason that we didn't add Undefined to PEP 484 and PEP 526: Having "another kind of None" will cause code everywhere to expect it. (Plus Guido didn't like it) -- Ivan
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