php decorator

<?php
class MyModel {
        const ABC="DEF\n";
        public function someBiz($arg) {
                echo($arg . "\n");
        }
        public function someBiz2($arg1, $arg2) {
                echo($arg1 . ',' . $arg2 . "\n");
        }
}
// ci loader is essentially doing this
$model_name = 'MyModel';
// only modify the class once
$methods = get_class_methods($model_name);
foreach($methods as $method) {
        runkit_method_copy($model_name, '_' . $method, $model_name, $method);
        runkit_method_redefine(
                $model_name,
                $method,
                '',
                'echo("intercepted\n"); $args = func_get_args();'.
                'return call_user_func_array(array($this, "_' . $method . '"), $args);',
                RUNKIT_ACC_PUBLIC
        );
}
$model = new $model_name();
$model->someBiz('hello');
echo($model::ABC);

在php里实现类似python的decorator，必须借助php extension。因为纯php的wrapper无法伪装所有的行为。比如$obj::const 这样的引用就是非法的。
上面代码的执行结果

intercepted
hello
DEF

验证两个问题，说明拦截成功，而且参数传递没有问题。在ubuntu上运行，这样安装runkit

sudo pear channel-discover zenovich.github.io/pear
sudo pecl install zenovich/runkit

在命令上启用

cat /etc/php5/cli/conf.d/20-runkit.ini
输出
extension=runkit.so

在fpm上启用

cat /etc/php5/fpm/conf.d/20-runkit.ini
输出
extension=runkit.so