oop - PHP: Is there no way to use a global variable inside an object constructor? -

i have php script intended user-editable, options set right @ beginning, including allowable extensions image files.

later on, want use in object constructor set whether file image or not.

$extensions = ["jpg", "jpeg", "gif", "png"];  class directory_entry {    function __construct($name) {      $this->name = $name;      $extension = pathinfo($name, pathinfo_extension);     $this->is_image = in_array(strtoupper($extension), $extensions); // throws error      $this->image = $this->is_image($name);    } } 

this doesn't work because can't call $extensions inside class(?). there way without including $extensions in every object of class? seems nuts declare objects

$files[] = new directory_entry($value, $extensions);

and have every instance of class have copy of same array?

why not create classe this?

class extensionsenum {     const images = ["jpg", "jpeg", "gif", "png"]; } 

then

use extensionsenum;  class directory_entry { ...     $this->is_image = in_array(strtoupper($extension), extensionsenum::images); // throws error ... }