Re: delete-generations or --delete-generations?

[zimoun]

Hi Raghav,

On Thu, 26 Aug 2021 at 21:04, Raghav Gururajan <rg@raghavgururajan.name> wrote:

> Why there is no '--' prefix to 'delete-generations' for `guix system`, 
> when there is for `guix pull` and `guix package`?

I speculate too. :-) I guess because the idea behind “guix system” is
one action at a time however “guix package” can compose actions in one
transaction (guix package --install=foo --remove=bar).  Using the
default CLI parser (SRFI-37), it seems easier for composing to use the
options (--<name-it>) than to extract actions.  For instance, if it was
“guix package <action>” as it is with “guix system”, then it is harder
to parse the composition, i.e.,

  guix package install foo remove bar

Aside the CLI parser is more work than just using ’args-fold’ from
SRFI-37, ambiguities happen: consider the case where ’remove’ is also a
package, for instance.

Then the other actions (--list-generations, --show, --search, etc.)
would inherit from this initial “guix package” design about composition
for a install/remove transactions.

Well, I agree that “guix system” is inconsistent with the rest of
commands.  First, “guix system” does not enjoy the typo hinter:

  $ guix system delte-generations
  guix system: error: delte-generations: unknown action

compared to:

  $ guix package --delte-generations
  guix package: error: delte-generations: unrecognized option
  hint: Did you mean `delete-generations'?

Well, although it is obviously fixable. ;-) Second, it leads to corner
cases as describe by the manual, for instance,

  $ guix system delete-generation -1
  guix system: error: 1: unrecognized option

here ’-1’ is considered by the parser as a short option, so one needs:

  $ guix system delete-generation -- -1

Issue which does not happen using “--delete-generation”. :-)

On the other hand, the composition is not totally true, for instance:

  $ guix package --show=cuirass --search="GNU hello"
  name: hello
  …

  $ guix package  --search="GNU hello" --show=cuirass
  name: cuirass
  …

although it is debatable to compose them. :-)


Ah consistent CLI, so complicated topic! ;-)


Cheers,
simon

PS: It reminds me issues with short-name accepting optional argument:

   guix package -I -p /tmp/profile # fails
   guix package -p /tmp/profile -I # works

<http://issues.guix.gnu.org/40549#19> where a next action is described
here <http://issues.guix.gnu.org/40549#22>. :-)