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Date: Mon, 03 Feb 2014 11:17:46 +0000
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Subject: Re: [PHP-DEV] Declare minimum PHP version required?
From: lester@lsces.co.uk (Lester Caine)

Yasuo Ohgaki wrote:
>>> > >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
>> >
>> >Why not? That's what PHP does - executing scripts.
>> >
>>> > >included, not when it is executed. I wouldn't write version_compare() and
>> >
>> >I don't understand - what is the difference? In PHP including and
>> >executing is the same thing.
>> >
>> >I think version_compare works just fine.
>
> I works, but it requires CPU time for it and evaluation is delayed at
> run time, not compile time. Isn't it nice to know requirement is not met?
>
> We may extend declare() more. For example, loaded extensions.
>
> declare(module='pgsql,openssl');
>
> With this, we could eliminate code like
>
> if (!extension_loaded('foo')) {
>    die('You need foo module');
> }
> if (!extension_loaded('bar')) {
>    die('You need bar module');
> }
>
> With opcache loaded extension check may be completely skipped.
>
> Evaluation at compile time and run time differs.

I don't see how one can eliminate checking if a module is available. I do not 
load MySQL on my systems so if someone tries to run a script requiring MySQL 
they need a warning that it's not available. The build of PHP running ensures 
that the available built in modules are of the right version, but it's the third 
party libraries that I need to ensure are compatible with the version of PHP I'm 
trying to run, and that the necessary extensions for that library are loaded. 
Stuff updated to PHP5.5 may not work on the systems that are still running 
PHP5.4 for compatibility reasons ...

-- 
Lester Caine - G8HFL
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