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Date: Sun, 08 Dec 2013 18:07:52 +0000
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To: Alexey Zakhlestin <indeyets@gmail.com>, 
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Subject: Re: [PHP-DEV] Introducing pragmas into PHP?
From: ellison.terry@gmail.com (Terry Ellison)

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On 08/12/13 17:14, Alexey Zakhlestin wrote:
>> I am suggestion the overload of constants of the form PHP_PRAGMA_XXX to
>> define PHP / Zend compiler / executor behaviours. This approach would be
>> BC to 5.3 unless, of course, the application already used PHP_PRAGMA_*
>> constants, in which case we might also need an allow_php_pragmas INI
>> parameter to globally enable/disable their interpretation.
> we already have declare() for this purpose exactly.
> http://docs.php.net/declare
>
> it might make sense to use it for more things
Alexey, perhaps you missed the subtlety of my example:

    namespace fred;
    const PHP_PRAGMA_ALLOW_OVERRIDE_BUILTINS=false;
    echo strlen("DDDD");

define() is a runtime function implemented by 
Zend/zend_builtin_functions.c:ZEND_FUNCTION(define).  The constant which 
is defines is not available until the DO_FCALL_BY_NAME opcode is itself 
executed sometime *after* the compile of the current source completes.

const is a syntactic construct that can be intercepted in 
zend_compile.c, etc.,  and therefore can condition the remainder of the 
compile of that source.  That's what pragmas do.

However, you are quite correct that:

    define('fred\PHP_PRAGMA_ALLOW_OVERRIDE_BUILTINS', false);
    include "some_other_php_file_in_namespace_fred.php";
    ...

would set the pragma for subsequent source scripts in the "fred" 
namespace, if we adopted this convention.

Hope this helps.  Terry

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