Re: Real constants

[Richard M. Stallman]

    Aren't user-defined constants useful in other languages? Isn't it
    useful per se to be able to set a symbol and guarantee that the user,
    or another module, is not going to change it by accident?

I don't see a need for this.

     Certainly
    Common Lisp is not above having constants

I don't want to add features to Emacs Lisp just because other
languages, even other Lisp dialects, have them.  That would be a
recipe for adding lots more features, each of which would be work to
maintain, work to document, etc.

    What do you ask for? An example? What if the constants define absolute
    sizes of external resources (like, for example,
    `bindat--fixed-length-alist') and every single attempt to change them
    could be considered an error (and possibly crash Emacs)?

That is a case where the feature would provide no practical benefit,
because the magnitude of the problem in practice is zero.  It would be
more elegant in some conceptual sense if these symbols could not be
altered.  But that would not translate into any benefit for Emacs
users, or for us Emacs maintainers.

    No, that's "I assumed the value of real constants in programming
    languages was way beyond needing a rationale"... Perhaps I'm assuming
    too much.

The question here is, "How will they help make Emacs better to edit
with?"