ср, 5 февр. 2020 г. в 04:27, Stefan Monnier <monnier@iro.umontreal.ca>:

> > Hmm, maybe no reason actually.  My thought was about providing some way
> for
> > user to autodetect :battery and :line-power device in his init.el and
> > explicitly write something like:
> >
> >   (setq battery-upower-device (battery-upower-device-autodetect
> :battery))
> >
> > So he states in the config, that he has upower and want error to be rised
> > if upower service is not available.
>
> But
>
>     (setq battery-status-function #'battery-upower)
>
> already does that in a more direct and reliable way, no?
>
>
Yes, reasonable indeed.

> If `battery.el` is loaded unintentionally, then all the custom vars will
> > have suitable values to have no warnings.  However if user explicitly set
> > `battery-upower-device` to invalid value, then warning will arise on
> > battery.el load.
>
> Exactly, and even if the user did not intend to use battery in this
> session (Elisp files can be loaded "spuriously").
>
> > Otherwise (no warning on invalid `battery-upower-device`), if upower
> > service is available - `battery-status-function` will be set to
> > upower, and `M-x battery RET` will produce N/A values, and there is no
> > clue for the user that he just have invalid value for the
> > `battery-upower-device`.
>
> No: `M-x battery` will emit the warning.
>
>
So `battery-upower` should check the correctness of the
`battery-upower-device` on every call?  It would make it heavier, but of
course more reliable, because user might change the value of the
`batter-upower-device` in runtime

We might have `nil` values for the `battery-upower-device` and
`battery-upower-line-power-device` meaning "autodetect".  This will require
additional call to D-Bus (battery-upower-device-list) on every call to
`battery-upower`, probably this is OK.  If user want extra speed he just
set right values for that vars.  Sounds good?

Having `nil` values for those defcustom vars, also won't require putting
them after all the functions

-- 
lg