On Apr 20, 2020, at 16:24, M.-A. Lemburg <[email protected]> wrote:
>
> On 20.04.2020 19:43, Andrew Barnert via Python-ideas wrote:
>>> On Apr 20, 2020, at 01:06, M.-A. Lemburg <[email protected]> wrote:
>>>
>>> The current version already strikes me as way too complex.
>>> It's by far the most complex piece of grammar we have in Python:
>>>
>>> funcdef: 'def' NAME parameters ['->' test] ':' [TYPE_COMMENT]
>>> func_body_suite
>>
>> But nobody’s proposing changing the function definition syntax here, only
>> the function call syntax. Which is a lot less hairy. It is still somewhat
>> hairy, but nowhere near as bad, so this argument doesn’t really apply.
>
> True, I quoted the wrong part of the grammar for the argument,
> sorry. I meant this part:
>
> https://docs.python.org/3/reference/expressions.html#calls
>
> which is simpler, but not really much, since the devil is in
> the details.
Let’s just take one of the variant proposals under discussion here, adding
::identifier to dict displays. This makes no change to the call grammar, or to
any of the call-related bits, or any other horribly complicated piece of
grammar. It just changes key_datum (a nonterminal referenced only in
dict_display) from this:
expression ":" expression | “**” or_expr
… to this:
expression ":" expression | “::” identifier | “**” or_expr
That’s about as simple as any syntax change ever gets.
Which is still not nothing. But you’re absolutely right that a big and messy
change to function definition grammar would have a higher bar to clear than
most syntax proposals—and for the exact same reason, a small and local change
to dict display datum grammar has a lower bar than most syntax proposals.
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