Find out if a method exists in a static class

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Find out if a method exists in a static class – Here in this article, we will share some of the most common and frequently asked about PHP problem in programming with detailed answers and code samples. There’s nothing quite so frustrating as being faced with PHP errors and being unable to figure out what is preventing your website from functioning as it should like php and static . If you have an existing PHP-based website or application that is experiencing performance issues, let’s get thinking about Find out if a method exists in a static class.

I want to check is a function exists in a library that I am creating, which is static. I’ve seen function and method_exists, but haven’t found a way that allows me to call them in a relative context. Here is a better example:

class myClass{
    function test1()
    {
        if(method_exists("myClass", "test1"))
        {
            echo "Hi";
        }
    }
    function test2()
    {
        if(method_exists($this, "test2"))
        {
            echo "Hi";
        }
    }
    function test3()
    {
        if(method_exists(self, "test3"))
        {
            echo "Hi";
        }
    }
}
// Echos Hi
myClass::test1();
// Trys to use 'self' as a string instead of a constant
myClass::test3();
// Echos Hi
$obj = new myClass;
$obj->test2();

I need to be able to make test 3 echo Hi if the function exists, without needing to take it out of static context. Given the keyword for accessing the class should be ‘self’, as $this is for assigned classes.

Solution :

static::class is available since PHP 5.5, and will return the “Late Static Binding” class name:

class myClass {
    public static function test()
    {
        echo static::class.'::test()';
    }
}

class subClass extends myClass {}

subClass::test() // should print "subClass::test()"

get_called_class() does the same, and was introduced in PHP 5.3

class myClass {
    public static function test()
    {
        echo get_called_class().'::test()';
    }
}

class subClass extends myClass {}

subClass::test() // should print "subClass::test()"

The get_class() function, which as of php 5.0.0 does not require any parameters if called within a class will return the name of the class in which the function was declared (e.g., the parent class):

class myClass {
    public static function test()
    {
        echo get_class().'::test()';
    }
}

class subClass extends myClass {}

subClass::test() // prints "myClass::test()"

The __CLASS__ magic constant does the same [link].

class myClass {
    public static function test()
    {
        echo __CLASS__.'::test()';
    }
}

class subClass extends myClass {}

subClass::test() // prints "myClass::test()"

Update:

Ahh, apologies. I was temporarily blind 🙂 You’ll want to use the magic constant __CLASS__

e.g.

if (method_exists(__CLASS__, "test3")) { echo "Hi"; }

for all situations… the best usage would be…

if method_exist(…) && is_callable(…)

For testing example:

class Foo {
  public function PublicMethod() {}
  private function PrivateMethod() {}
  public static function PublicStaticMethod() {}
  private static function PrivateStaticMethod() {}
}

$foo = new Foo();

$callbacks = array(
  array($foo, 'PublicMethod'),
  array($foo, 'PrivateMethod'),
  array($foo, 'PublicStaticMethod'),
  array($foo, 'PrivateStaticMethod'),
  array('Foo', 'PublicMethod'),
  array('Foo', 'PrivateMethod'),
  array('Foo', 'PublicStaticMethod'),
  array('Foo', 'PrivateStaticMethod'),
);

foreach ($callbacks as $callback) {
  var_dump($callback);
  var_dump(method_exists($callback[0], $callback[1])); // 0: object / class name, 1: method name
  var_dump(is_callable($callback));
  echo str_repeat('-', 40), "n";
}

Source here

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