Question

I was thinking today at how all the OOP works.

And i was thinking: Wouldn’t be great to check if a method exists using a given text value ?

So, if i have a text function_name_in_text_format, how do i check if the method function_name_in_text_format exists ?

I heard of a solution, something with using $$, but could not find real examples

Answer 1

You can use the is_callable() function.

Verify that the contents of a variable can be called as a function.
This can check that a simple variable contains the name of a valid
function, or that an array contains a properly encoded object and
function name.

There are also the function_exists() and method_exists() functions that can be used as the name indicates.

The method for using $$ is known as variable variables.

A variable variable takes the value of a variable and treats that as
the name of a variable.

Included below is an example for using is_callable():
<?php
// How to check a variable to see if it can be called
// as a function.

//
//  Simple variable containing a function
//

function someFunction() 
{
}

$functionVariable = 'someFunction';

var_dump(is_callable($functionVariable, false, $callable_name));  // bool(true)

echo $callable_name, "\n";  // someFunction

//
//  Array containing a method
//

class someClass {

  function someMethod() 
  {
  }

}

$anObject = new someClass();

$methodVariable = array($anObject, 'someMethod');

var_dump(is_callable($methodVariable, true, $callable_name));  //  bool(true)

echo $callable_name, "\n";  //  someClass::someMethod

?>