Using constant to call a function with that name in PHP

Question

I have the following code:

$this->load->library('dummyLib');
$this->dummyLib->dummyLibFunction();

(I am using a PHP-Framework that works like that)

Now I want to be able to change the different libraries depending on a constant that I have defined priviously:

defined('LIB') OR define('LIB', 'dummy');

Which I can use like $myLibrary = LIB

As I have to load that library in different locations I want my code to automatically adjust to that constant. I know that function calls are possible with variables like this:

$myFunctionNameInThisVariable = 'test';
$this->$myFunctionNameInThisVariable();

This will call $this->test()

Can I do the same with constants? Or do I always have to use an additional variable?

Answer 1

To answer your question, let's compare function calls:

a normal function call is:

$this->functionName();

a function call with defined constant is

$this->CONSTANT_NAME();

As in php functions' names are case insensitive , php cannot understand what you want to do - call a function CONSTANT_NAME or replace constant CONSTANT_NAME with is real value. So, there's only one option here - find a function by provided name ( CONSTANT_NAME ) and execute it.

So, the answer is: yes , you should use a variable in this case.

Also, there's another option with using call_user_func_ methods:

function callMe()
{
    echo '123';
}
define ('CALL_ME', 'callMe');
call_user_func(CALL_ME);
// yep, this works: https://3v4l.org/tbRrr