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Date: Sat, 19 Nov 2016 01:05:30 +0700
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To: David Rodrigues <david.proweb@gmail.com>
Subject: Re: [PHP-DEV] Declare directive to change engine version basis
From: php-lists@koalephant.com (Stephen Reay)

Hi David,

If you wanted to do this, couldn=E2=80=99t you simply use the following, =
already:

set_error_handler(
	function (int $err_severity, string $err_msg, string $err_file, =
int $err_line, array $err_context) {
		throw new ErrorException($err_msg, 0, $err_severity, =
$err_file, $err_line)
	},
	E_DEPRECATED
);

?

> On 18 Nov 2016, at 23:18, David Rodrigues <david.proweb@gmail.com> =
wrote:
>=20
> Hello.
>=20
> I like to propose a creation of a new declare() directive that allows
> "emulates a future engine version". And where I say engine I mean PHP
> itself.
>=20
> -
>=20
> It should works like it (eg. for engine version "7.0.13"):
>=20
>    declare( {{parameter}} =3D {{php_version_id}} );
>=20
>    // Examples (one of that):
>    declare( engine_version =3D 70013 ); // or
>    declare( php_version =3D 70013 );
>=20
> -
>=20
> By default, this declaration is not defined (null or 0), then will not
> do anything to engine if it's not declared on script.
>=20
> -
>=20
> This declaration could be done at:
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>    - First execution file.php (bootstrap): then all application will
> follow this engine rules;
>    - Any file.php: then only current file will follow this rules (to
> override locally first declaration);
>    - php.ini: to set this declaration as default to all applications
> (optional);
>=20
> -
>=20
> What it does: in pratical, if the engine will deprecated or change
> something on future versions (mainly causing BCs), you should wait for
> a new major version (eg. 7.x -> 8.x). With this declaration you could
> emulates a future version to prepares your scripts to a new major
> version.
>=20
> -
>=20
> Let working on an example from: =
https://wiki.php.net/rfc/deprecations_php_7_2
>=20
> The (unset) cast should not be used anymore because it's have not any
> effect (just return null, but not affect the expression or variable).
> Let supposed that this deprecation is done at 7.2.0 (id 70200), then
> if I'm using this version and I declare engine_version like:
>=20
>    - no declared or null: just a deprecation notice;
>    - declare as 70200 or higher: error, (unset) cast doesn't exists
> (or something like that)
>=20
> -
>=20
> Then, what the engine_version does is set some variable to engine that
> could check if it could be executed on declared version, then
> developers can code their files to future versions without need wait
> for it.
>=20
> -
>=20
> If the installed version is different of declared version, then the
> engine will always consider the lowest version between both. For
> instance: if installed version is 70201 (7.2.1) and declared version
> is 70205 (7.2.5), then engine will consider changes from 70201 (7.2.1,
> once that installed is lower). And again: engine will works
> differently only if declaration is done, else, it'll works by
> deprecation notice, for instance.
>=20
> -
>=20
> What happen on engine code is something like that (pseudo-code):
>=20
>    int engine_version () {
>        return (int) engine_version_declaration;
>    }
>=20
>    cast type unset () {
>        if (engine_version() >=3D 70201) {
>            fatal(cast doesn't supported);
>        }
>=20
>        notice(deprecated);
>        return null;
>    }
>=20
>=20
> --=20
> David Rodrigues
>=20
> --=20
> PHP Internals - PHP Runtime Development Mailing List
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>=20