Re: [PATCH 1/2] pathspec magic: add '^' as alias for '!'

[Brandon Williams <bmwill@google.com>]

On 02/07, Linus Torvalds wrote:
> 
> From: Linus Torvalds <torvalds@linux-foundation.org>
> Date: Tue, 7 Feb 2017 21:05:28 -0800
> Subject: [PATCH 1/2] pathspec magic: add '^' as alias for '!'
> 
> The choice of '!' for a negative pathspec ends up not only not matching
> what we do for revisions, it's also a horrible character for shell
> expansion since it needs quoting.
> 
> So add '^' as an alternative alias for an excluding pathspec entry.
> 
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> ---
>  pathspec.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/pathspec.c b/pathspec.c
> index 7ababb315..ecad03406 100644
> --- a/pathspec.c
> +++ b/pathspec.c
> @@ -224,6 +224,12 @@ static const char *parse_short_magic(unsigned *magic, const char *elem)
>  		char ch = *pos;
>  		int i;
>  
> +		/* Special case alias for '!' */
> +		if (ch == '^') {
> +			*magic |= PATHSPEC_EXCLUDE;
> +			continue;
> +		}
> +
>  		if (!is_pathspec_magic(ch))
>  			break;

I like adding '^' to be an alias for excluding patterns.  There have
been numerous times where I have wanted to use exclude patterns and
forgotten that I've needed to do some escape magic to get my shell to
leave '!' alone.

The only issue I see with doing this is that if a user supplies an
exclude pattern for a command which doesn't support exclude pathspec
magic the unsupported_magic() function will have slightly cryptic
output.

git cmd -- :^dir

would produce some output which says:
':^dir': pathspec magic not supported by this command: 'exclude' (mnemonic: '!')

And the user may scratch their head for a second since they didn't
supply the '!' character, but rather '^'.  That being said I think it
should be fine since the long name of the magic is also printed so the
user should be able to figure out what's wrong.  I also don't think
there are any users of pathspecs which disallow exclude magic so this
may not even be an issue.

-- 
Brandon Williams