Re: [PATCH 1/2] do not mangle short options which take arguments

From: Clemens Buchacher <drizzd@aon.at>
Date: Oct 2, 2009, 07:36 UTC
Message-ID: <20091002073628.GA9444@localhost>
In-Reply-To: <20091002061159.GA24892@coredump.intra.peff.net>

On Fri, Oct 02, 2009 at 02:11:59AM -0400, Jeff King wrote:

> I thought the proposal was to disallow just cuddling of the value when
> the switch was combined with others. So you would disallow "git commit
> -ammend" but it would still be legal to do "git commit -am foo". Your
> patch disallows the latter.

Yes, that syntax looks reasonable. I expect this to be more involved, so I will rework the patch once we agree on whether or not we want it at all.

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> To be honest, I am not sure that even the more restricted proposal is
> that good an idea. You are introducing a heuristic to guess at what is a
> typo or error from the user; when your guess is wrong, the user will be
> annoyed (doubly so if it is buried deep in a script, which this change
> will also impact).

Yes, that can happen. On the other hand, the "-ammend" typo actually did happen. And what I'm even more worried about are ambiguities like

  $ git commit -uno <path>
  $ git commit -nou <path>

which are interpreted as one of

  $ git commit --untracked-files=no <path>
  $ git commit --untracked-files --no-verify --only <path>

depending only on the order of the switches. I was actually surprised that I could find an example so easily. But the fact alone that it's possible feels like an accident waiting to happen.

> On the other hand, the cuddled value already has some DWYM magic (it
> recognizes -amend), so it is already a little bit unsafe to use

Well, an error message is a lot safer than executing something you did not intend.

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> So I don't feel _too_ strongly. I am just concerned that we are
> introducing some DWYM magic that is not really going to help many people
> out, and is just going to make understanding the rules for option
> parsing more complex, and introduce the possibility (albeit slim) of
> breaking people's scripts and trained fingers.

But it makes the rules simpler, because it removes ambiguities such as the one above.

Yes, we deliberately allow users to shoot themselves in the foot. But they should have to use at least a long option to do it.

Clemens