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

[Emanuel Berg via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

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'?

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