Re: [PATCH v2 1/1] completion: load completion file for external subcommand

From: SZEDER Gábor <szeder.dev@gmail.com>
Date: Apr 29, 2018, 13:08 UTC
Message-ID: <CAM0VKjkmQObwiUBnf+xydKS1rO5B20HdWsdBjsQLDhcndoM7ng@mail.gmail.com>
In-Reply-To: <20180429111533.GA31974@furore>

On Sun, Apr 29, 2018 at 1:15 PM, Florian Gamböck <mail@floga.de> wrote:

Show 30 quoted lines

> On 2018-04-25 16:40, SZEDER Gábor wrote:
>>
>> In my previous emails I overlooked the _completion_loader() helper
>> function.
>>
>> It seems that this function does almost exactly what we want.  It was
>> introduced along with dynamic completion loading back in 20c05b43, so it's
>> available for us even in older LTS/Enterprise releases.  Since cad3abfc it's
>> a wrapper around __load_completion() and thus benefits from all the
>> improvements, notably searching for completion scripts in a user-specified
>> directory ($BASH_COMPLETION_USER_DIR) or in the user's home directory
>> ($XDG_DATA_HOME or ~/.local/...) as well.  It loads the matching completion
>> script, but does not call the completion function unconditionally.
>
>
> Sounds good so far.
>
>> The "almost" refers to he case when _completion_loader() can't find a
>> completion script with a matching name to load, and then registers the
>> _minimal() completion function for the given command to do basic path
>> completion as fallback.  I don't think this matters in practice, because in
>> this case the given command is a git command in its dashed form, e.g.
>> 'git-diff-index', and those have been deprecated for a long time.
>
>
> I sense a problem here. If I have a directory with a file xyzfoobar in it,
> and I type `git xyz`, with no defined subcommand that starts with these
> letters, then minimal bashcomp would give me `git xyzfoobar`, which can of
> course not execute. This can be unintuitive for users, as in: "If it can't
> be executed correctly, then why does it even suggest such a completion?"

I'm not sure I understand the problem. After 'git xyz<TAB>' (note there is no space between 'xyz' and <TAB>) we try to complete the name of a git command, not options of a git command. This means:

  - At this point we don't look for a _git_xyz() function, so we'll
    return from __git_main() before even reaching the piece of code
    your patch modifies.

  - There are (presumably) no commands starting with 'xyz', so we
    don't list any commands.  Bash will then fall back to its own
    filename completion, and that's where that 'xyzfoobar' will come
    from.  It has been behaving like this basically since forever.

And after 'git xyz <TAB>' (this time with space) we already complete the next word, not 'xyz'.

Show 9 quoted lines

>> I think all you need to do is run a
>> s/__load_completion/_completion_loader/ on your patch and update the commit
>> message with relevant bits from the above discussion.
>
>
> I can do that, no problem. But prior to that I want to be sure that you are
> okay with the above mentioned drawback. Will the behavior be acceptable in
> this case? Or should we try to somehow "undo" the minimal completion
> afterwards?

As explained above, I don't think there is any drawback here. Or at least not any new drawback that your patch is introducing. Or I'm completely missing your point; certainly a possibility, it's early Sunday afternoon, after all :)