clarity needed for the non-sealed keyword

[forax at univ-mlv.fr]

----- Mail original -----
> De: "Pravin Jain" <pravin at zensoftech.co.in>
> À: "Remi Forax" <forax at univ-mlv.fr>
> Cc: "Brian Goetz" <brian.goetz at oracle.com>, "Florian Weimer" <fw at deneb.enyo.de>, "amber-dev"
> <amber-dev at openjdk.java.net>
> Envoyé: Vendredi 9 Octobre 2020 16:39:59
> Objet: Re: clarity needed for the non-sealed keyword

> Hi Remi,

Hi,

> 
> My point here was that in the JEP for keyword management for Java
> Language, this option has not been considered, while discussing all
> the other options.

see the answer of Brian.

Furthermore, we have tried to use # and ` in other features in the past.
The symbol # was proposed before using :: for method reference, because it is used in the javadoc to reference a method, but after testing a prototype, people found that # was too big/bold visually.
The symbol ` was proposed for raw strings, a feature that was abandoned but it may be used for string interpolation in the future.

> 
> Thanks and regards,
> Pravin

regards,
Rémi

> 
> On Fri, Oct 9, 2020 at 12:47 PM <forax at univ-mlv.fr> wrote:
>>
>> ----- Mail original -----
>> > De: "Pravin Jain" <pravin at zensoftech.co.in>
>> > À: "Brian Goetz" <brian.goetz at oracle.com>
>> > Cc: "Florian Weimer" <fw at deneb.enyo.de>, "Remi Forax" <forax at univ-mlv.fr>,
>> > "amber-dev" <amber-dev at openjdk.java.net>
>> > Envoyé: Vendredi 9 Octobre 2020 08:08:10
>> > Objet: Re: clarity needed for the non-sealed keyword
>>
>> > Hi Brian,
>> >
>> > One of the points which has not been considered, is using an ASCII
>> > letter which has not been used by any other standard tokens(operator,
>> > separator) e.g. using one of # or ` (hash or backtick)
>> > Yes, it may not be natural, so was the _(underscore) when it was used
>> > in a numeric literal, but readibility was good _(underscore),
>> > similarly using a # instead of
>> > hyphen in new keywords may also be considered. It would not have the
>> > problem of ambiguity, and readibility will not be as bad.
>>
>> using one or several hyphens in names, usually referred as kebab-case because if
>> the word is using two hyphens it looks like a spit, is pretty commons in
>> several programming languages [1] (ok, most of them are dialects of LISP).
>>
>> >
>> > The hyphenated keywords require a look ahead, which consumes white
>> > spaces including new-line characters. This would be possible for
>> > compilers and IDEs to manage to some extend but, a very big ask for
>> > the REPL tools like jshell.
>>
>> Nope, no lookahead,
>> a lookahead is when the parser needs to read one (or more) tokens in advance,
>> here, the work is done by the lexer before the token reaches the parser.
>>
>> What you need is a lexer with some rules enabled or disabled given the context,
>> it's a fairly old technique, lex, the lexer from the 70ies [2], has lexing
>> modes.
>> And it solves both the need for contextual keywords like "module" or "record"
>> that have different meaning depending where they are declared and hyphen
>> keywords.
>>
>> >
>> > I tried using non-sealed on a separate line with jshell to define a
>> > non-sealed class, but it is getting tokenized as three tokens.
>> > I could easily define an abstract class by starting with abstract on a
>> > separate line, but this doesn't work for non-sealed keyword.
>>
>> If it doesn't work with jshell, please submit a bug !
>>
>> >
>> > I understand that # may not look good, but if could be used, then there are less
>> > problems.
>>
>> Nope, most people will never think that the keyword "non-sealed" requires some
>> bookkeepings. And that's exactly what we want.
>>
>> >
>> > Thanks and regards,
>> > Pravin
>>
>> regards,
>> Rémi
>>
>> [1]
>> https://en.wikipedia.org/wiki/Naming_convention_(programming)#Multiple-word_identifiers
>> [2] https://en.wikipedia.org/wiki/Lex_(software)
>>
>> >
>> > On Fri, Oct 9, 2020 at 1:10 AM Brian Goetz <brian.goetz at oracle.com> wrote:
>> >>
>> >>
>> >> > But why does the keyword contain a “-”?  Why wasn't “nonsealed” good
>> >> > enough?
>> >>
>> >> The rationale for the creation of hyphenated keywords is well
>> >> documented.  See, for example:
>> >>
>> >> http://mail.openjdk.java.net/pipermail/amber-spec-experts/2019-January/000945.html
>> >>
>> >> and
>> >>
>> >> https://openjdk.java.net/jeps/8223002
>> >>
>> >>
>> >
>> >
>> > --
>> > Pravin Jain
>> > (M)+91-9426054269
> 
> 
> 
> --
> Pravin Jain
> (M)+91-9426054269