php 检查方法是否存在于同一个类中
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Check if method exists in the same class
提问by Rafael
So, method_exists()requires an object to see if a method exists. But I want to know if a method exists from within the same class.
所以，method_exists()需要一个对象来查看一个方法是否存在。但我想知道同一个类中是否存在一个方法。
I have a method that process some info and can receive an action, that runs a method to further process that info. I want to check if the method exists before calling it. How can I achieve it?
我有一个方法可以处理一些信息并可以接收一个动作，它运行一个方法来进一步处理该信息。我想在调用之前检查该方法是否存在。我怎样才能实现它？
Example:
例子：
class Foo{
public function bar($info, $action = null){
//Process Info
$this->$action();
}
}
回答by Rajdeep Paul
You can do something like this:
你可以这样做：
class A{
public function foo(){
echo "foo";
}
public function bar(){
if(method_exists($this, 'foo')){
echo "method exists";
}else{
echo "method does not exist";
}
}
}
$obj = new A;
$obj->bar();
回答by Flosculus
Using method_existsis correct. However if you want to conform to the "Interface Segregation Principle", you will create an interface to perform introspection against, like so:
使用method_exists是正确的。但是，如果您想符合“接口隔离原则”，您将创建一个接口来执行自省，如下所示：
class A
{
public function doA()
{
if ($this instanceof X) {
$this->doX();
}
// statement
}
}
interface X
{
public function doX();
}
class B extends A implements X
{
public function doX()
{
// statement
}
}
$a = new A();
$a->doA();
// Does A::doA() only
$b = new B();
$b->doA();
// Does B::doX(), then remainder of A::doA()
回答by Calimero
method_exists()accepts either a class name or object instance as a parameter. So you could check against $this
method_exists()接受类名或对象实例作为参数。所以你可以检查$this
http://php.net/manual/en/function.method-exists.php
http://php.net/manual/en/function.method-exists.php
Parameters?
objectAn object instance or a class name
method_nameThe method name
参数?
object对象实例或类名
method_name方法名
回答by Jeliu Jelev
The best way in my opinion is to use __call magic method.
我认为最好的方法是使用 __call 魔术方法。
public function __call($name, $arguments)
{
throw new Exception("Method {$name} is not supported.");
}
Yes, you can use method_exists($this ...) but this is the internal PHP way.
是的，您可以使用 method_exists($this ...) 但这是 PHP 的内部方式。
