如何将另一个文件中的变量赋值给类常量？

Question

I have a set of API keys that are constant across my codebase - I have a dev key and a live key. They are stored in their own 'keys.php' file.

I have a class that handles accessing the API and I am storing the keys in the class as class constants.

I want to be able to swap out the dev keys for live keys and access them in a static method of my class.

This works fine when I assign the class constant like this:

const API_USER_NAME = 'user_name';

But want to store the keys in their own file, and include them into the class file, and define those constants as such:

const API_USER_NAME = $user_name;

But apparently I can't assign a variable to a constant, even though that variable will not change value during execution of the program.

Is there another way I can use a variable to assign to a constant? Or at least, keep they keys in their centralized file, but still access them in the static methods of my class?

Answer 1

You could simply define your keys themselves as constants:

keys.php

const KEY_USER_NAME = 'user_name';
const KEY_USER_AGE = 'user_age';
// ...

Class

require $path_to_somewhere . '/keys.php';

class YourClass 
{
  const API_USER_NAME = KEY_USER_NAME;
  const API_USER_AGE = KEY_USER_AGE;

  // ...
}