patchcontrib/git-jump: support alias expansion

Hi,

I have been meaning to send this patch for a while, which teaches the 'git-jump' script how to respect user aliases for commands like 'diff', 'merge', and 'grep'.

I often find myself parsing the output of 'git diff' (which I spell 'g di') in less, and then wanting to jump to some specific diff in a file, i.e., by running 'git jump diff -- <filename>'.

But, I am so used to typing 'di' instead of 'diff', that I often write the later invocation as 'g jump di -- <filename>', and 'git-jump' complains that it doesn't know what 'di' means.

Let's rectify that by teaching it how to expand alises, which is implemented in the patch below.

Thanks, Taylor

Taylor Blau (1):
  contrib/git-jump/git-jump: support alias expansion

 contrib/git-jump/README   | 4 ++++
 contrib/git-jump/git-jump | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

-- 2.22.0

When a caller of 'git-jump' has, say, the alias 'di' assigned to 'diff', it can be cumbersome to remember to type 'git jump diff' instead of the shorthand '... di' that they are used to.

Let's teach 'git-jump' to expand these aliases before calling the mode-specific subroutine. Do so by fetching the configuration value of 'alias.$1', defaulting to "$1" in the case that no alias is set.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 contrib/git-jump/README   | 4 ++++
 contrib/git-jump/git-jump | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

On Wed, Sep 04, 2019 at 01:55:03PM -0400, Taylor Blau wrote:

I guess it's worth noting that this does _not_ respect extra options given to the various modes. For example, if I alias 'diff' to 'diff --minimal', we will try and invoke the function "mode_diff --minimal", which doesn't make sense.

Perhaps we could take the output of this through "| awk '{ print $1 }'" to discard any extra options, but it feels like a bit of a hack.

Personally, I'm not bothered by this, but I also don't use aliases to add "default" options to any git sub-commands. But, I don't know if other people do, in which case they may want to chime in here.

Thanks in advance for your thoughts.

Thanks, Taylor

On Wed, Sep 04, 2019 at 01:55:00PM -0400, Taylor Blau wrote:

Hmm. I'm not exactly _opposed_ to this patch, but it does feel like it's weirdly conflating git commands with jump modes. Which just happen to use some of the same verbs, but not not always (e.g., "mode_ws").

And as you note, aliases may carry along options which do not make any sense for jump modes (or they might; we pass command-line options to diff and grep, so it's possible the alias could do something useful).

Your case would be equally helped if the tool allowed any non-ambiguous prefix to be used. But it wouldn't if somebody had "alias.foo = diff" or something. So I dunno.

I solved this for myself long ago with a mix of git and shell aliases:

  $ git help vgrep
  'vgrep' is aliased to 'jump grep'
  
  $ type d
  d is aliased to `git jump diff'
  
  $ type m
  m is aliased to `git jump merge'

For fun, here's a patch that does the prefix thing (though the $0 hackery may be too much; we list the modes by hand in the usage, after all).