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Date: Mon, 3 Feb 2014 15:58:06 +0900
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Subject: Declare minimum PHP version required?
From: yohgaki@ohgaki.net (Yasuo Ohgaki)

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Hi all,

I thought it might be good for us to have declaring minimum PHP version
required to execute script.
http://jp1.php.net/manual/en/control-structures.declare.php

Something like
<?php
declare(php_version>='5.6.0');
// or PHP_VERSION_ID? using = as minimum as it could be a little faster
// and no change in declare() syntax.
declare(php_version=50600);

If version mismatches, raise compile error and exit. Something like

Compile error: PHP 5.6.0 or later is required to compile script. Your PHP
version is 5.x.x.

The same thing can be done by version_compare() and die(), but it does not
make much sense executing script only to check PHP version and die,
especially for libraries. For library, it is preferred to fail when it is
included, not when it is executed. I wouldn't write version_compare() and
die() for libraries, but I may use it if it's a declare(). If this is
adopted widely, it may help transition to higher versions hoping users to
consider compile error more seriously.

Issue would be current behavior for unsupported declaration.
$ php -r "declare(php_version=050600);"
Warning: Unsupported declare 'php_version' in Command line code on line 1
It does not raise E_ERROR, but E_WARNING.

Just an idea.
Any comments?

--
Yasuo Ohgaki
yohgaki@ohgaki.net

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