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

[Jean Louis <bugs@gnu.support>]

* Emanuel Berg via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org> [2022-03-15 06:16]:
> Stefan Monnier via Users list for the GNU Emacs text editor wrote:
> 
> >> I assume it would be fairly easy to code such a macro
> >> (using `boundp'), but maybe it exists already?
> >
> > AFAIK it doesn't exist yet. The reason for it is that it is
> > not often useful. Typically there are two cases:
> >
> > - If the var exist, you want to set it and if not you have
> >   no fallback. In that case, it is typically harmless to set
> >   the var even when it doesn't exist, so the code just uses
> >   `setq` without bothering to test `boundp`.
> >
> > - If the var exist you want to set it, and if it doesn't you
> >   want to do something else. In that case, the something
> >   else tends to depend on the specifics so (if (boundp 'foo)
> >   (setq foo ..) ...) is about s good as it gets.
> 
> If it exists set it with `setq'. If it doesn't exist, create
> and set it ... with `setq'?

Hahahahha -- exactly.

-- 
Jean

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