Adding variables inside constants

Question

I'm using constants for my error messages inside the Views, and I want to be able to use variables inside them for easier management.

Most of my constants looks like this:

const SUCCESSFULLY_REGISTERED = "<p class='success'>Registration successful!.</p>";

What I want to do is to use a variable for the css class, so that it's easier to change them all in one place. This is what I've tried:

const SUCCESSFULLY_REGISTERED = "<p class='$this->cssClassSuccess'>Registration successful!.</p><p>Log in with the username and password you registered with.</p>";

By some reason that doesn't work and raises the error message below. Why is that and how can this be done in a way that works?

Parse error: syntax error, unexpected '"' in .../View/RegisterView.php on line 15

Answer 1

This is not possible if you define a constant.

Manual: "The value must be a constant expression, not (for example) a variable, a property, a result of a mathematical operation, or a function call."

Constant Manual php.net
Constant Expression