Re: environment variable handling cleanup ?

[Vincent Legoll]

Hello,

since no one objected to the idea, I'm going forward with this.

On Mon, Mar 23, 2020 at 9:55 AM Hartmut Goebel
<address@hidden> wrote:
> Well, I did not count how often this is used, but (guix built utils
> update-env) might benefit from this, to.

I don't know if you meant that (guix build utils) was the right place
to put those helpers, or if you were hinting me at a place where I
can use them, or both.

It looks like there is something that they can replace in this file:
(wrap-script ... (update-env ...))

But...
[reordering email content]

> > Another question is the usefulness of the separator parameter,
> > as I think all target cases use ":", so hardcoding it would be a
> > sensible choice.
>
> I doubt there is a need for different separators. The path separator is
> defined to be ":" in Posix. So I'd suggest to use a hardcoded value.

To replace (update-env ...) code, I will need to keep separator as a
parameter, since some cases in the match-lambda don't use an
hardcoded ":".

What should I do there ?
Can you clarify ?

> > There's also the added (or (getenv ...) "") which is not present in
> > all target cases.
>
> I suggest to default the value to #f (False), since - depending on the
> variables semantic - it may make a difference whether the variabel is
> empty or actually unset. This is especially true when used within a
> programming language like Scheme which has a notion of "False" - which
> env-vars do not have.

OK, I'll do that, I'll just remove the (or (getenv ...) default-value) as the
return value for getenv on a non-existent variable is already #f

Thanks

-- 
Vincent Legoll