Subject: Re: [PATCH 1/2] parse-options: expand $HOME on filename options

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Thu, 22 Feb 2018 14:38:39 +0100

On Thu, Feb 22 2018, Duy Nguyen jotted:

> On Thu, Feb 15, 2018 at 5:46 AM, Ævar Arnfjörð Bjarmason
> <[email-masked]> wrote:
>> In general I'm mildly negative on adding this, for every user like Doron
>> who'll be less confused by a hack like this, you'll have other users
>> who'll be confused about git inexplicably working with ~ in the middle
>> of strings, even though;
>>
>>     $ echo git init --template ~/path
>>     git init --template /home/avar/path
>>     $ echo git init --template=~/path
>>     git init --template=~/path
>
> If you have a directory named '~', I expect you are already used to
> prefixing it with './' because '~' will be expanded in many places
> where you might want to avoid.

Indeed. I've never had this use-case, just saying if it's being changed
it makes sense to have a small test for it somewhere.

>> I think it makes more sense to just leave such expansion to the shell,
>> and not try to magically expand it after the fact, since it's both
>> confusing (user: why does this work with git and not this other
>> program?), and as shown above changes existing semantics.
>>
>> We'll also be setting ourselves up for more disappointed users who'll
>> notice that e.g. `git clone file://~/path` doesn't work, but `git clone
>> file://$HOME/path` does, requiring more hacks to expand ~ in more
>> codepaths. Will they also expact `git log -G~` to find references to
>> their homedir in their dotfiles.git?
>>
>> I think this way lies madness, and it's better to just avoid it.
>
> Well. That's a bit extreme, I think if we add this then we handle case
> by case in future when it makes sense, not blindly expanding '~'
> everywhere.
>
> The problem I have with this --template=~/path is tab-completion
> actually completes the path, which (mis)leads me to think the command
> will accept '~/' too. But this looks like a bug in git-completion.bash
> though, it's a bit eager in completing stuff (or maybe it completes
> "--template ~/path" and "--template=~/path" the same way).

Ah I see, so you're doing "git init --template=~/<TAB>".

> I don't feel strongly about this. I'm OK with dropping these patches
> if people think it's not a good idea (then I will try to fix
> git-completion.bash not to complete '~' in this case).

I don't feel strongly about it either, just mildly negative on
introducing magic that gives you different behavior than shells do by
default.

I wonder if the consistency with the tab completion wouldn't be better
done by teaching the tab completion to just expand --template=~/<TAB> to
e.g. --template=/home/duy/.

On my (Debian) system doing e.g.:

    echo $HOME/bin/<TAB>

Will expand to:

    echo /home/avar/bin/

Maybe we could intercept that in the completion and ~ to the value of
$HOME. It would give completion that did the right thing, without the
expectation that ~ is going to be magic in some places and not others.

>> But I think that if we're going to keep it it needs some tests & docs to
>> point confused users to.