> On Aug 3, 2023, at 17:59, Carsten Bormann <cabo@xxxxxxx> wrote:
>
> On 3. Aug 2023, at 23:47, Tim Bray <tbray@xxxxxxxxxxxxxx> wrote:
>>
>> I really do think that in RFCs, when there’s something that’s optional, it’s really better to say why it’s optional and what might motivate choosing one option or another.
>
> But they are not “optional".
Fair. I was mainly referring to examples like your C return statement.
>
> They aren’t there:
>
> filter-selector = "?" S logical-expr
>
> You can use other features of the language to put some there, if you really want to:
>
> logical-expr = logical-or-expr
> logical-or-expr = logical-and-expr ...
> logical-and-expr = basic-expr ...
>
> basic-expr = paren-expr / ...
>
> paren-expr = [logical-not-op S] "(" S logical-expr S ")"
> ; parenthesized expression
>
> You could use ?!(!(foo)) as well, and I also wouldn’t say that !(!(…)) is “optional”.
>
> (I wouldn’t mind adding a note explaining why the parentheses are in the examples where they are.
> But I don’t know why we put them there.)
That works for me.
Joe
>
> Grüße, Carsten
>
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