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Date: Sun, 20 Oct 2019 17:44:48 -0400
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To: Rowan Tommins <rowan.collins@gmail.com>
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Subject: Re: [PHP-DEV] Adding explicit intent for SWITCH/CASE fall through?
From: mike@newclarity.net (Mike Schinkel)

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> On Oct 20, 2019, at 7:28 AM, Rowan Tommins <rowan.collins@gmail.com> =
wrote:
> On 20/10/2019 01:39, Mike Schinkel wrote:
>> Not yet having experience working on PHP's parser I do not know how =
it is configured nor what about the design of PHP requires keywords =
unable to be used as constants, class names, function or method names. I =
know this is a tangent but that seems like a requirement designed to =
simplify the parser maybe, and not because of any logical requirement. =
So I assume whatever word was used for this would also have to be a =
reserved keyword?  Or not?
>=20
>=20
> I don't know the full implications in the parser, but at the language =
level, any constant can technically appear where this keyword would. =
That is, the following is valid right now:
>=20
> const fallthrough=3Dnull;
> fallthrough;
>=20
> It doesn't do anything, but it's valid because any expression on its =
own is a valid statement, and a constant on its own is a valid =
expression.

Thank you for clarifying that.

Still, I wonder if a reserved word really needs to disallow function, =
method, class and trait names, which are more problematic to me.  I have =
often wanted to name a class 'List`.  And I have often wanted to name a =
method `do()`, `continue()`, `end()` and `try()`. =20

Seems like a needless limitation thus forcing the use of less =
appropriate symbol naming.

> Interestingly, that actually makes a single keyword *more* appealing =
to me, because it means you can get *forwards* compatibility by writing =
this:
>=20
> if ( PHP_VERSION < 80000 && ! defined('fallthrough') ) {
>     define('fallthrough', null);
> }

Oh, that is interesting!=20

Too bad you can't define a constant to call an initializer method.

-Mike=

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