Q:

Can I assign a function path or deeper value to a constant within a class?

I read somewhere at some point that this can't be done, but I'm wondering if there is just another way to go about it. 
Right now I have the following...
define('CUSTOM_THEME_BACKEND_PATH', get_stylesheet_directory());
But I would like it to be within a class like the following...
const CUSTOM_THEME_BACKEND_PATH = get_stylesheet_directory();

Then I can run something like the following... 
MyConstantClass::CUSTOM_THEME_BACKEND_PATH . '/path/to/file'

Is there anyway I can assign more complicated values to a constant within a class?
Reference: http://php.net/manual/en/language.oop5.constants.php
I would like to protect my constant by the class, but also I am creating a theme that has quite a bit of options and I have to define those values quite a bit. I would like to cut down on that, which would also let me change things in the future with less work. 
I would like to assign something like the above and also the following... 
const Option = get_options_data('custom-theme-custom-assets', 'enable-custom-skins');

Then if I can do something like the following... 
if (isset(MyConstantClass::Option) && MyConstantClass::Option == 'true'){}

Is there a way I can do this? 

A:

You can use the "mutable" keyword to have some of the class's fields changeable, and set them in the following lines.
However, this is highly irregular and should be considered carefully.

