PHP method_exists 检查类的方法是否存在
method_exists
method_exists — 检查类的方法是否存在
说明
bool method_exists ( object $object , string $method_name )
如果 method_name 所指的方法在 object 所指的对象类中已定义，则返回 TRUE，否则返回 FALSE。
Example #1 method_exists() 例子
<?php $directory= newDirectory(‘.’);var_dump(method_exists($directory,’read’));?>以上例程会输出：bool(true)
PHP method_exists note #1
Just to mention it: both method_exists() and is_callable() return true for inherited methods:<?phpclassParentClass { functiondoParent() { }}classChildClassextendsParentClass{ }$p= newParentClass();$c= newChildClass();// all return truevar_dump(method_exists($p,’doParent’));var_dump(method_exists($c,’doParent’));var_dump(is_callable(array($p,’doParent’)));var_dump(is_callable(array($c,’doParent’)));?>
PHP method_exists note #2
Using method_exists inside an object’s __call() method can be very usefull if you want to avoid to get a fatal error because of a limit in function nesting or if you are calling methods that dont exist but need to continue in your application: <?phpclassSomething {/** * Call a method dynamically * * @param string $method * @param array $args * @return mixed */public function__call($method,$args) { if(method_exists($this,$method)) { returncall_user_func_array(array($this,$method),$args); }else{ throw newException(sprintf(‘The required method “%s” does not exist for %s’,$method,get_class($this))); } } }?>
PHP method_exists note #3
As noted [elsewhere] method_exists() does not care about the existence of __call(), whereas is_callable() does: <?phpclassTest { public functionexplicit( ) {// …} public function__call($meth,$args) {// …} }$Tester= newTest();var_export(method_exists($Tester,’anything’));// falsevar_export(is_callable(array($Tester,’anything’)));// true?>
PHP method_exists note #4
Be warned that the class must exist before calling method exists from an eval statement otherwise you will get a Signal Bus error.
PHP method_exists note #5
It wasn’t spelled out but could be inferred: method_exists() also works on interfaces.<?phpvar_dump (method_exists(“Iterator”,”current”));// bool(true)?>
PHP method_exists note #6
If you want to check in a class itself if a method is known you may do so with magic variable __CLASS__<?phpclassA {__construct($method){ returnmethod_exists(__CLASS__,$method); } private functionfoo(){ }}$test= newA(‘foo’);//should return true?>You might also use the method describe below with <?php in_array()?>trick but I consider this one here easier and more readable and well, the way it is intended toi be done ;)
PHP method_exists note #7
Hi, Here is a useful function that you can use to check classes methods access e.g whether it is public, private or static or both.. here it goes: <?php // Example classclassmyClass{ private$private1; static$static1; public$public1; public functionpubl() { } private functionpriv() { } private static functionprivstatic() { } public static functionpublstatic() { } static functionmytest() { } }// The function uses the reflection class that is built into PHP!!! // The purpose is to determine the type of a certain method that exifunctionis_class_method($type=”public”,$method,$class) {// $type = mb_strtolower($type);$refl= newReflectionMethod($class,$method); switch($type) { case”static”: return$refl->isStatic(); break; case”public”: return$refl->isPublic(); break; case”private”: return$refl->isPrivate(); break; } }var_dump(is_class_method(“static”,”privstatic”,”myClass”));// true – the method is private and also static..var_dump(is_class_method(“private”,”privstatic”,”myClass”));// true – the method is private and also static..var_dump(is_class_method(“private”,”publstatic”,”myClass”));// False the methos is public and also static not private // you get the idea.. I hope this helps someone..?>
PHP method_exists note #8
This function is case-insensitive (as is PHP) and here is the proof:<?phpclassA { public functionFUNC() { echo’*****’; }}$a= newA();$a->func();// *****var_dump(method_exists($a,’func’));// bool(true)?>
PHP method_exists note #9
As mentioned before, is_callable and method_exists report all methods callable even if they are private/protected and thus actually not callable. So instead of those functions you may use following work-around which reports methods as supposed to.<?phpclassFoo1 { public functionbar() { echo”I’m private Foo1::bar()”; }}classFoo2{ private functionbar() { echo”I’m public Foo2::bar()”; }}$f1=newFoo1;$f2=newFoo2;if(is_callable(array($f1,”bar”))) { echo”Foo1::bar() is callable”;} else { echo”Foo1::bar() isn’t callable”;}if(is_callable(array($f2,”bar”))) { echo”Foo2::bar() is callable”;} else { echo”Foo2::bar() isn’t callable”;}if(in_array(“bar”,get_class_methods($f1))) { echo”Foo1::bar() is callable”;} else { echo”Foo1::bar() isn’t callable”;}if(in_array(“bar”,get_class_methods($f2))) { echo”Foo2::bar() is callable”;} else { echo”Foo2::bar() isn’t callable”;}?>outputFoo1::bar() is callable (correct)Foo2::bar() is callable (incorrect)Foo1::bar() is callable (correct)Foo2::bar() isn’t callable (correct)?>
在编程中，我们有的时候需要判断某个类中是否包含某个方法，除了使用反射机制，PHP还提供了method_exists()和is_callable()方法进行判断。那么两则区别是什么呢？
已知类文件如下：class Student{
private $alias=null; private $name=”; public function __construct($name){
$this->name=$name;
} private function setAlias($alias){
$this->alias=$alias;
} public function getName(){
return $this->name;
}
}12345678910111213
当方法是private，protected类型的，method_exists会报错，is_callable会返回false。
实例
下面是判断某一对象中是否存在方法getName
通过method_exists实现$xiaoming=new Student(‘xiaoming’);if (method_exists($xiaoming, ‘getName’)) {
echo ‘exist’;
}else{ echo ‘not exist’;
}exit();1234567
输出exist
通过is_callable实现$xiaoming=new Student(‘xiaoming’);if (is_callable(array($xiaoming, ‘getName’))) {
echo ‘exist’;
}else{ echo ‘not exist’;
}exit();1234567
输出exist
下面是判断某一对象中是否存在方法setAlias 当使用method_exists的时候报错如下
当使用is_callable的时候，输出not exist
今天的文章php 类方法是否存在,PHP函数method_exists检查类是否存在和与is_callable()的区别分享到此就结束了，感谢您的阅读。
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