PHP中插件机制实现:mediawiki的钩子机制
mediawiki的扩展机制很多，钩子就是其中之一。不过，其钩子机制是通过函数来实现的。简单地说，钩子机制通过三个方面来实现：
1、注册钩子；
2、放置钩子（事件：event handle);
3、运行钩子；
具体如下：
一、注册钩子
如：ArticleDelete
*Define function:
function fnMyHook( &$article, &$user, &$reason, &$error ) { ... }
*Attach hook:
$wgHooks['ArticleDelete'][] = 'fnMyHook';
二、钩子句柄
wfRunHooks($event, $args = array()) 这里面就是wfRunHooks('ArticleDelete');放在在适当的位置
三、钩子的运行
/** * Because programmers assign to $wgHooks, we need to be very * careful about its contents. So, there's a lot more error-checking * in here than would normally be necessary. */function wfRunHooks($event, $args = array()) { global $wgHooks; // Return quickly in the most common case if ( !isset( $wgHooks[$event] ) ) { return true; } if (!is_array($wgHooks)) { throw new MWException("Global hooks array is not an array!\n"); return false; } if (!is_array($wgHooks[$event])) { throw new MWException("Hooks array for event '$event' is not an array!\n"); return false; } foreach ($wgHooks[$event] as $index => $hook) { $object = null; $method = null; $func = null; $data = null; $have_data = false; $closure = false; /* $hook can be: a function, an object, an array of $function and $data, * an array of just a function, an array of object and method, or an * array of object, method, and data. */ if ( is_array( $hook ) ) { if ( count( $hook ) < 1 ) { throw new MWException("Empty array in hooks for " . $event . "\n"); } else if ( is_object( $hook ) ) { $object = $wgHooks[$event][$index]; if ( $object instanceof Closure ) { $closure = true; if ( count( $hook ) > 1 ) { $data = $hook; $have_data = true; } } else { if ( count( $hook ) < 2 ) { $method = "on" . $event; } else { $method = $hook; if ( count( $hook ) > 2 ) { $data = $hook; $have_data = true; } } } } else if ( is_string( $hook ) ) { $func = $hook; if ( count( $hook ) > 1) { $data = $hook; $have_data = true; } } else { throw new MWException( "Unknown datatype in hooks for " . $event . "\n" ); } } else if ( is_string( $hook ) ) { # functions look like strings, too $func = $hook; } else if ( is_object( $hook ) ) { $object = $wgHooks[$event][$index]; if ( $object instanceof Closure ) { $closure = true; } else { $method = "on" . $event; } } else { throw new MWException( "Unknown datatype in hooks for " . $event . "\n" ); } /* We put the first data element on, if needed. */ if ( $have_data ) { $hook_args = array_merge(array($data), $args); } else { $hook_args = $args; } if ( $closure ) { $callback = $object; $func = "hook-$event-closure"; } elseif ( isset( $object ) ) { $func = get_class( $object ) . '::' . $method; $callback = array( $object, $method ); } elseif ( false !== ( $pos = strpos( $func, '::' ) ) ) { $callback = array( substr( $func, 0, $pos ), substr( $func, $pos + 2 ) ); } else { $callback = $func; } // Run autoloader (workaround for call_user_func_array bug) is_callable( $callback ); /* Call the hook. */ wfProfileIn( $func ); $retval = call_user_func_array( $callback, $hook_args ); wfProfileOut( $func ); /* String return is an error; false return means stop processing. */ if ( is_string( $retval ) ) { global $wgOut; $wgOut->showFatalError( $retval ); return false; } elseif( $retval === null ) { if ( $closure ) { $prettyFunc = "$event closure"; } elseif( is_array( $callback ) ) { if( is_object( $callback ) ) { $prettyClass = get_class( $callback ); } else { $prettyClass = strval( $callback ); } $prettyFunc = $prettyClass . '::' . strval( $callback ); } else { $prettyFunc = strval( $callback ); } throw new MWException( "Detected bug in an extension! " . "Hook $prettyFunc failed to return a value; " . "should return true to continue hook processing or false to abort." ); } else if ( !$retval ) { return false; } } return true;}
就这三下！注意，其中重要的一个函数，
call_user_func_array(); //php函数
主要是这个函数起作用。
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