dl
(PHP 3, PHP 4 )
dl -- Loads a PHP extension at runtime
Description
int dl ( string library)
Loads the PHP extension given by the parameter library.
The library parameter is only the filename of the extension
to load which also depends on your platform. For example,
the sockets extension (if compiled as a shared module, not
the default!) would be called sockets.so on Unix platforms
whereas it is called php_sockets.dll on the Windows platform.
Returns TRUE on success or FALSE on failure. If the functionality
of loading modules is not available (see Note) or has been
disabled (either by turning it off enable_dl or by enabling
safe mode in php.ini) an E_ERROR is emitted and execution
is stopped. If dl() fails because the specified library
couldn't be loaded, in addition to FALSE an E_WARNING message
is emitted.
Use extension_loaded() to test whether a given extension
is already available or not. This works on both built-in
extensions and dynamically loaded ones (either through php.ini
or dl()).
Example 1. dl() examples
<?php
// Example loading an extension based on OS
if (!extension_loaded('sqlite')) {
if (strtoupper(substr(PHP_OS, 0, 3) == 'WIN')) {
dl('php_sqlite.dll');
} else {
dl('sqlite.so');
}
}
// Or, the PHP_SHLIB_SUFFIX constant is available as of
PHP 4.3.0
if (!extension_loaded('sqlite')) {
$prefix = (PHP_SHLIB_SUFFIX == 'dll') ? 'php_' : '';
dl($prefix . 'sqlite.' . PHP_SHLIB_SUFFIX);
}
?>
The directory where the extension is loaded from depends
on your platform:
Windows - If not explicitly set in the php.ini, the extension
is loaded from c:\php4\extensions\ by default.
Unix - If not explicitly set in the php.ini, the default
extension directory depends on
whether PHP has been built with --enable-debug or not
whether PHP has been built with (experimental) ZTS (Zend
Thread Safety) support or not
the current internal ZEND_MODULE_API_NO (Zend internal
module API number, which is basically the date on which
a major module API change happened, e.g. 20010901)
Taking into account the above, the directory then defaults
to <install-dir>/lib/php/extensions/ <debug-or-not>-<zts-or-not>-ZEND_MODULE_API_NO,
e.g. /usr/local/php/lib/php/extensions/debug-non-zts-20010901
or /usr/local/php/lib/php/extensions/no-debug-zts-20010901.
Note: dl() is not supported in multithreaded Web servers.
Use the extensions statement in your php.ini when operating
under such an environment. However, the CGI and CLI build
are not affected !
Note: dl() is case sensitive on Unix platforms.
Note: This function is disabled in safe mode.
See also Extension Loading Directives and extension_loaded().
