bug#58282: Distinguishing glasses-mode display

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 04 Oct 2022 18:09:53 +0000
> From: uzibalqa <uzibalqa@proton.me>
> Cc: dimech@gmx.com, 58282@debbugs.gnu.org
> 
> > You cannot simply assign the value to this variable. Look at its
> > defcustom form to understand what is missing.
> > 
> > And anyway, what does this have to do with the bug report? You are
> > asking basic Emacs Lisp questions.
> 
> Because I can use utf, I can easily distinguish between code and glasses display.
> This feature solves my problem.

So do use it.  It is possible and supported, just not by a simple
setq.

Here's the defcustom of that option from glasses.el:

  (defcustom glasses-separator "_"
    "String to be displayed as a visual separator in identifiers.
  It is used both for adding missing separators and for replacing separators
  defined by `glasses-original-separator'.  If you don't want to add missing
  separators, set `glasses-separator' to an empty string.  If you don't want to
  replace existent separators, set `glasses-original-separator' to an empty
  string."
    :type 'string
    :set 'glasses-custom-set
    :initialize 'custom-initialize-default)

What does the :set attribute tell you?