php中trait單例和調用執行個體詳解

Trait單例

執行個體如下

<?phptrait singleton {        /**     * private construct, generally defined by using class     */    //private function construct() {}        public static function getInstance() {        static $_instance = NULL;        $class = CLASS;        return $_instance ?: $_instance = new $class;    }        public function clone() {        trigger_error('Cloning '.CLASS.' is not allowed.',E_USER_ERROR);    }        public function wakeup() {        trigger_error('Unserializing '.CLASS.' is not allowed.',E_USER_ERROR);    }}/*** Example Usage*/class foo {    use singleton;        private function construct() {        $this->name = 'foo';    }}class bar {    use singleton;        private function construct() {        $this->name = 'bar';    }}$foo = foo::getInstance();echo $foo->name;$bar = bar::getInstance();echo $bar->name;

調用trait方法

雖然不很明顯，但是如果Trait的方法可以被定義為在普通類的靜態方法，就可以被調用

執行個體如下

<?php trait Foo {     function bar() {         return 'baz';     } } echo Foo::bar(),"\\n"; ?>

CLASS和TRAIT

CLASS 返回 use trait 的 class name，TRAIT返回 trait name

樣本如下

<?phptrait TestTrait {    public function testMethod() {        echo "Class: " . CLASS . PHP_EOL;        echo "Trait: " . TRAIT . PHP_EOL;    }}class BaseClass {    use TestTrait;}class TestClass extends BaseClass {}$t = new TestClass();$t->testMethod();//Class: BaseClass//Trait: TestTrait