PHP callback: Is there an equivalent for ::class for a method of a class?

问题

The bounty expires in 7 days. Answers to this question are eligible for a +50 reputation bounty. Blackbam wants to draw more attention to this question:

A good solution shows a possibility to do this without passing a string but something which can be validated. If this is possible with two or three lines of codes using ReflectionClass this would totally be o.k. - I am just looking for a good way to solve this in a way such that I see an error in the IDE in case a method does not exist.

In PHP it is possible to get a full class name via class name resolution like this:

Example:

namespace Name\Space;
class ClassName {}

echo ClassName::class;

Output: Name\Space\ClassName

This is better than using the string Name\Space\ClassName directly in the code because code introspection especially in IDEs can find an error directly.

I wonder if there is something similar for methods of a class - this would be specifically useful for callback functions.

This is how you can basically can pass a callback:

$a = function($callback,$arg) { return $callback($arg); }

$a('getInfo',5);

Instead of passing a string here (which might change), I would prefer to do something like this:

$a(MyClass::class::getInfo,5);

With I "go to declaration" click in the IDE I could go directly to getInfo plus I see errors in case with method does not exist anymore. Is there a way to achieve what I want to do here?

回答1:

In fact, you work with callable type. And PHP allows setting method/function name only as a string. But if you use classes and objects you will have a different way to set callback. For example:

$a = function($callback, $arg) { 
   return call_user_func($callback, $arg)); 
}

// call a static method of the class with 
// using fullname space and method name as a string
$a('Name\Space\MyClass::getInfo',5); 

// call a static method of the class 
// with using ::class 
$a([MyClass::class, 'getInfo'], 5);

// call a method of an object 
$myObject = new MyClass();
$a([$myOject, 'getInfo'], 5);

来源：https://stackoverflow.com/questions/66238766/php-callback-is-there-an-equivalent-for-class-for-a-method-of-a-class