[PATCH] Make '!' aliases more useful

[PATCH] Make '!' aliases more useful

[Johannes Schindelin]

When an alias starts with an exclamation mark, the rest is interpreted
as a shell command. However, all arguments passed to git used to be
ignored.

Now you can have an alias like

	$ git config alias.e '!echo'

and

	$ git e Hello World

does what you expect it to do.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---

	I have this in my $HOME/.gitconfig:

		[alias]
			debug = !GIT_PAGER= gdb --args git

	which allows me to debug, say "git log a..b" by saying "git debug 
	log a..b".

 git.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/git.c b/git.c
index 8ea70da..32e8aa9 100644
--- a/git.c
+++ b/git.c
@@ -205,6 +205,21 @@ static int handle_alias(int *argcp, const char ***argv)
 	git_config(git_alias_config);
 	if (alias_string) {
 		if (alias_string[0] == '!') {
+			if (*argcp > 1) {
+				int i, sz = PATH_MAX;
+				char *s = xmalloc(sz), *new_alias = s;
+
+				add_to_string(&s, &sz, alias_string, 0);
+				free(alias_string);
+				alias_string = new_alias;
+				for (i = 1; i < *argcp &&
+					!add_to_string(&s, &sz, " ", 0) &&
+					!add_to_string(&s, &sz, (*argv)[i], 1)
+					; i++)
+					; /* do nothing */
+				if (!sz)
+					die("Too many or long arguments");
+			}
 			trace_printf("trace: alias to shell cmd: %s => %s\n",
 				     alias_command, alias_string + 1);
 			ret = system(alias_string + 1);
-- 
1.5.2.2.3276.gf2524-dirty

Re: [PATCH] Make '!' aliases more useful

[Theodore Tso]

On Sun, Jul 01, 2007 at 10:51:58PM +0100, Johannes Schindelin wrote:
> 
> When an alias starts with an exclamation mark, the rest is interpreted
> as a shell command. However, all arguments passed to git used to be
> ignored.
> 
> Now you can have an alias like
> 
> 	$ git config alias.e '!echo'
> 
> and
> 
> 	$ git e Hello World
> 
> does what you expect it to do.

But what if you don't want the argument passed at the end of the
alias, but somewhere else?  I suspect the better answer would be to
support $* and $1, $2, $3, et. al interpolation, no?  It was on my
list of things to do when I had a spare moment, but I never got around
to it.

					- Ted

Re: [PATCH] Make '!' aliases more useful

[Johannes Schindelin]

Hi,

On Mon, 2 Jul 2007, Theodore Tso wrote:

> On Sun, Jul 01, 2007 at 10:51:58PM +0100, Johannes Schindelin wrote:
> > 
> > When an alias starts with an exclamation mark, the rest is interpreted
> > as a shell command. However, all arguments passed to git used to be
> > ignored.
> > 
> > Now you can have an alias like
> > 
> > 	$ git config alias.e '!echo'
> > 
> > and
> > 
> > 	$ git e Hello World
> > 
> > does what you expect it to do.
> 
> But what if you don't want the argument passed at the end of the
> alias, but somewhere else?  I suspect the better answer would be to
> support $* and $1, $2, $3, et. al interpolation, no?  It was on my
> list of things to do when I had a spare moment, but I never got around
> to it.

There is a point where you do not want to complicate git, but rather write 
a script. This is such a point IMHO.

Ciao,
Dscho

Re: [PATCH] Make '!' aliases more useful

[Theodore Tso]

On Mon, Jul 02, 2007 at 04:55:24PM +0100, Johannes Schindelin wrote:
> > But what if you don't want the argument passed at the end of the
> > alias, but somewhere else?  I suspect the better answer would be to
> > support $* and $1, $2, $3, et. al interpolation, no?  It was on my
> > list of things to do when I had a spare moment, but I never got around
> > to it.
> 
> There is a point where you do not want to complicate git, but rather write 
> a script. This is such a point IMHO.

Such a point exists, I agree, but I would draw after $* and $1/$2/$3
interpolation.  There is a lot more value that gets added with
positional arguments support, and it makes git aliases more usable on
platforms such as Windows where scripting capability is much more
limited.

Regards,

					- Ted

Re: [PATCH] Make '!' aliases more useful

[Junio C Hamano]

Theodore Tso <tytso@mit.edu> writes:

> On Mon, Jul 02, 2007 at 04:55:24PM +0100, Johannes Schindelin wrote:
>> > But what if you don't want the argument passed at the end of the
>> > alias, but somewhere else?  I suspect the better answer would be to
>> > support $* and $1, $2, $3, et. al interpolation, no?  It was on my
>> > list of things to do when I had a spare moment, but I never got around
>> > to it.
>> 
>> There is a point where you do not want to complicate git, but rather write 
>> a script. This is such a point IMHO.
>
> Such a point exists, I agree, but I would draw after $* and $1/$2/$3
> interpolation.  There is a lot more value that gets added with
> positional arguments support, and it makes git aliases more usable on
> platforms such as Windows where scripting capability is much more
> limited.

That actually sounds sensible, but you could alias

	!sh -c 'command $2 $1 $3'

to reorder the parameters, couldn't you?
	

Re: [PATCH] Make '!' aliases more useful

[Theodore Tso]

On Mon, Jul 02, 2007 at 04:11:21PM -0700, Junio C Hamano wrote:
> > Such a point exists, I agree, but I would draw after $* and $1/$2/$3
> > interpolation.  There is a lot more value that gets added with
> > positional arguments support, and it makes git aliases more usable on
> > platforms such as Windows where scripting capability is much more
> > limited.
> 
> That actually sounds sensible, but you could alias
> 
> 	!sh -c 'command $2 $1 $3'
> 
> to reorder the parameters, couldn't you?

Um, how would that work on the Windows platform?

(I'm assuming here that we are trying to support Windows better, since
there are projects such as Mozilla, and MySQL that care very much
about first class Windows support.  We could say this isn't important
enough, and that would be fine; but I wanted to at least raise the
question.)

						- Ted

Re: [PATCH] Make '!' aliases more useful

[Johannes Schindelin]

Hi,

On Mon, 2 Jul 2007, Theodore Tso wrote:

> On Mon, Jul 02, 2007 at 04:11:21PM -0700, Junio C Hamano wrote:
> > > Such a point exists, I agree, but I would draw after $* and $1/$2/$3
> > > interpolation.  There is a lot more value that gets added with
> > > positional arguments support, and it makes git aliases more usable on
> > > platforms such as Windows where scripting capability is much more
> > > limited.
> > 
> > That actually sounds sensible, but you could alias
> > 
> > 	!sh -c 'command $2 $1 $3'
> > 
> > to reorder the parameters, couldn't you?
> 
> Um, how would that work on the Windows platform?
> 
> (I'm assuming here that we are trying to support Windows better, since
> there are projects such as Mozilla, and MySQL that care very much
> about first class Windows support.  We could say this isn't important
> enough, and that would be fine; but I wanted to at least raise the
> question.)

Windows support for those people unwilling to use cygwin amounts to 
anything, but a command line interface. Since aliases are _bound_ to 
the command line, I do not really get your point here.

In my view of things, for Windows support it is first of all important to 
get rid of the dependency on bash in the core parts. Then we should 
continue on the work Han-Wen did with his gub, and produce a proper 
Windows-clicky-style installer which installs git-gui with a proper 
Windows Start Menu item. But of course, then we should brace ourselves for 
a lot of clueless^Winterested users.

Ciao,
Dscho

Re: [PATCH] Make '!' aliases more useful

[Theodore Tso]

On Tue, Jul 03, 2007 at 02:37:43AM +0100, Johannes Schindelin wrote:
> Windows support for those people unwilling to use cygwin amounts to 
> anything, but a command line interface. Since aliases are _bound_ to 
> the command line, I do not really get your point here.

You're right of course.  <small>Never mind...</small>

						- Ted

Re: [PATCH] Make '!' aliases more useful

[Johannes Sixt]

Theodore Tso wrote:
> 
> On Mon, Jul 02, 2007 at 04:11:21PM -0700, Junio C Hamano wrote:
> > > Such a point exists, I agree, but I would draw after $* and $1/$2/$3
> > > interpolation.  There is a lot more value that gets added with
> > > positional arguments support, and it makes git aliases more usable on
> > > platforms such as Windows where scripting capability is much more
> > > limited.
> >
> > That actually sounds sensible, but you could alias
> >
> >       !sh -c 'command $2 $1 $3'
> >
> > to reorder the parameters, couldn't you?
> 
> Um, how would that work on the Windows platform?

Shouldn't be a problem for Cygwin users, nor for MinGW port users. The
latter need a Bourne shell anyway for the various scripted git tools.

-- Hannes

Re: [PATCH] Make '!' aliases more useful

[Alex Riesen]

On 7/2/07, Theodore Tso <tytso@mit.edu> wrote:
> On Mon, Jul 02, 2007 at 04:55:24PM +0100, Johannes Schindelin wrote:
> > > But what if you don't want the argument passed at the end of the
> > > alias, but somewhere else?  I suspect the better answer would be to
> > > support $* and $1, $2, $3, et. al interpolation, no?  It was on my
> > > list of things to do when I had a spare moment, but I never got around
> > > to it.
> >
> > There is a point where you do not want to complicate git, but rather write
> > a script. This is such a point IMHO.
>
> Such a point exists, I agree, but I would draw after $* and $1/$2/$3
> interpolation.  There is a lot more value that gets added with
> positional arguments support, and it makes git aliases more usable on
> platforms such as Windows where scripting capability is much more
> limited.

I don't think it is _possible_ to make it work on Windows properly: you have
to quote the arguments with whitespaces as there is nothing like argv there
(windows programs don't use command line, so it does not exist).
As the quoting is implemented in the programs the rules are all different
and mostly suboptimal.

Re: [PATCH] Make '!' aliases more useful

[Johannes Schindelin]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 2082 bytes --]

Hi,

On Tue, 3 Jul 2007, Alex Riesen wrote:

> On 7/2/07, Theodore Tso <tytso@mit.edu> wrote:
> > On Mon, Jul 02, 2007 at 04:55:24PM +0100, Johannes Schindelin wrote:
> > > > But what if you don't want the argument passed at the end of the
> > > > alias, but somewhere else?  I suspect the better answer would be to
> > > > support $* and $1, $2, $3, et. al interpolation, no?  It was on my
> > > > list of things to do when I had a spare moment, but I never got around
> > > > to it.
> > >
> > > There is a point where you do not want to complicate git, but rather
> > write
> > > a script. This is such a point IMHO.
> > 
> > Such a point exists, I agree, but I would draw after $* and $1/$2/$3
> > interpolation.  There is a lot more value that gets added with
> > positional arguments support, and it makes git aliases more usable on
> > platforms such as Windows where scripting capability is much more
> > limited.
> 
> I don't think it is _possible_ to make it work on Windows properly: you have
> to quote the arguments with whitespaces as there is nothing like argv there
> (windows programs don't use command line, so it does not exist).

Since the "!" aliases use system() (i.e. no argv, but a plain string as 
parameter), my patch already does that. It quotes the arguments properly.

> As the quoting is implemented in the programs the rules are all different
> and mostly suboptimal.

You mean the programs that could be called via "!" aliases? Yes, that is 
right. And there is also the problem that you have to convert path names 
if you are working on Windows, because of this c:\&@!§$ braindamage.

However, in this case Junio's idea to use the shell to do the hard work is 
again an alternative:

	[alias]
		alex = !sh -c 'd:\program.exe $(cygpath -w "$1")'

FWIW I do not think that executing the shell from time to time is a big 
problem. It's only that I would like to get rid of the dependency on perl 
and bash for the plain Windows user, who will not dare to leave the gui 
into the command line jungle where there be bisons, yaccs and kills.

Ciao,
Dscho