Accessing a class constant using a simple variable which contains the name of the constant

Question

I'm trying to access a class constant in one of my classes:

const MY_CONST = "value"; 

If I have a variable which holds the name of this constant like this:

$myVar = "MY_CONST"; 

Can I access the value of MY_CONST somehow?

self::$myVar 

does not work obviously because it is for static properties. Variable variables does not work either.

Answer 1

There are two ways to do this: using the constant function or using reflection.

Constant Function

The constant function works with constants declared through define as well as class constants:

class A {     const MY_CONST = 'myval';      static function test()     {         $c = 'MY_CONST';         return constant('self::'. $c);     } }  echo A::test(); // output: myval 

Reflection Class

A second, more laborious way, would be through reflection:

$ref = new ReflectionClass('A'); $constName = 'MY_CONST'; echo $ref->getConstant($constName); // output: myval 

Answer 2

There is no syntax for that, but you can use an explicit lookup:

print constant("classname::$myConst"); 

I believe it also works with self::.