Challenge 2 / 3

Suppose you want to change the value of a constant. Check out the following code:

class GasPlanet
{
    const MATERIAL_AMMONIA = 'ammonia';
}

<?php
// ...

GasPlanet::MATERIAL_AMMONIA = 'helium';

Is this legal?

Yes, but it's not recommended. Constants are values that are not meant to be modified.

No, unless you removed the const MATERIAL_AMMONIA = 'ammonia'; from GasPlanet. Constants can only be set once either via the const keyword, or by setting them from outside the class.

Nope - changing constants is totally not allowed, ever.

Yes, though it's recommended to change constants from inside the class where they are declared (i.e. GasPlanet).

Rewatch the video