Re: Is there a way of setting a variable only when it exists?

[Eli Zaretskii]

> From: Marcin Borkowski <mbork@mbork.pl>
> Date: Mon, 14 Mar 2022 07:00:33 +0100
> 
> I'd like to be able to say something like
> 
> (setq-safe hello "world")
> 
> so that `hello' is set to `"world"' if it is an existing variable (e.g.,
> defined by `defvar') and an error is raised if `hello' does not exist.
> 
> Rationale: I'm setting an internal Emacs variable.  At the same time,
> I submitted a feature request to turn it into a user option, so that
> it's possible that in a future version of Emacs it's going to change its
> name (it has two dashes in it).  I want to be warned then that I need to
> change my `init.el' accordingly.
> 
> I assume it would be fairly easy to code such a macro (using `boundp'),
> but maybe it exists already?

Why not just use boundp?