xargs should be a builtin

xargs should be a builtin

[Dave Yost]

Many’s the time I’ve wanted to use it to invoke a shell function.

Surely others have felt this lack.

Re: xargs should be a builtin

[Frank Terbeck]

Dave Yost wrote:
> Many’s the time I’ve wanted to use it to invoke a shell function.

autoload -Uz zargs
man zshcontrib | less -p '^  *zargs *\['


Regards, Frank

Problems with zargs (Was: xargs should be a builtin)

[Stephane Chazelas]

2012-04-11 09:44:48 +0200, Frank Terbeck:
> Dave Yost wrote:
> > Many’s the time I’ve wanted to use it to invoke a shell function.
> 
> autoload -Uz zargs
> man zshcontrib | less -p '^  *zargs *\['
[...]

By the way, there seems to be some issues with zargs:

~$ zargs a b '' -- print -rl
a
b
~$ zargs a -- print -rl ''
a
~$ zargs -e a '' print -rl
a print -rl
~$ zargs --eof= a '' print -rl
a
~$ echo $ZSH_VERSION $ZSH_PATCHLEVEL
4.3.17 Debian

-- 
Stephane

Re: Problems with zargs (Was: xargs should be a builtin)

[Peter Stephenson]

On Wed, 11 Apr 2012 11:06:42 +0100
Stephane Chazelas <stephane.chazelas@gmail.com> wrote:
> By the way, there seems to be some issues with zargs:
> 
> ~$ zargs a b '' -- print -rl
> a
> b
> ~$ zargs a -- print -rl ''
> a
> ~$ zargs -e a '' print -rl
> a print -rl
> ~$ zargs --eof= a '' print -rl
> a

It helps if everyone always says explicitly what the problem actually
is, it saves lots of guesswork.

I've come up with the following for the problems I understand, but I'm
sure it could do with a bit more prodding.

Index: Functions/Misc/zargs
===================================================================
RCS file: /cvsroot/zsh/zsh/Functions/Misc/zargs,v
retrieving revision 1.6
diff -p -u -r1.6 zargs
--- Functions/Misc/zargs	14 Aug 2011 13:40:53 -0000	1.6
+++ Functions/Misc/zargs	11 Apr 2012 16:14:48 -0000
@@ -167,11 +167,11 @@ if [[ $eof == -(e|-eof) ]]; then ((end=A
 elif (( $#eof )); then end=$argv[(i)${eof##-(e|-eof=)}]
 else end=$argv[(i)--]
 fi
-local -a args call command; command=( ${argv[end+1,-1]} )
+local -a args call command; command=( "${(@)argv[end+1,-1]}" )
 
 if (( $opts[(I)-(null|0)] ))
-then set -- ${(ps:\000:)argv[1,end-1]}
-else set -- $argv[1,end-1]
+then set -- "${(@ps:\000:)argv[1,end-1]}"
+else set -- "${(@)argv[1,end-1]}"
 fi
 
 if [[ -n $command ]]
@@ -187,7 +187,7 @@ local execute='
     then print -u2 -r -- "$call"
     fi
     eval "{
-	\$call
+	\"\${(@)call}\"
     } $bg"'
 local ret=0 analyze='
     case $? in
@@ -275,11 +275,11 @@ do
 	((ARGC)) || break
 	for (( end=l; end && ${(c)#argv[1,end]} > s; end/=2 )) { }
 	(( end > n && ( end = n ) ))
-	args=( $argv[1,end] )
+	args=( "${(@)argv[1,end]}" )
 	shift $((end > ARGC ? ARGC : end))
 	if (( $#i ))
-	then call=( ${command/$i/$args} )
-	else call=( $command $args )
+	then call=( "${(@)command/$i/$args}" )
+	else call=( "${(@)command}" "${(@)args}" )
 	fi
 	if (( ${(c)#call} > s ))
 	then

-- 
Peter Stephenson <p.w.stephenson@ntlworld.com>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/

Re: Problems with zargs (Was: xargs should be a builtin)

[Stephane Chazelas]

2012-04-11 17:15:39 +0100, Peter Stephenson:
> On Wed, 11 Apr 2012 11:06:42 +0100
> Stephane Chazelas <stephane.chazelas@gmail.com> wrote:
> > By the way, there seems to be some issues with zargs:
> > 
> > ~$ zargs a b '' -- print -rl
> > a
> > b
> > ~$ zargs a -- print -rl ''
> > a
> > ~$ zargs -e a '' print -rl
> > a print -rl
> > ~$ zargs --eof= a '' print -rl
> > a
> 
> It helps if everyone always says explicitly what the problem actually
> is, it saves lots of guesswork.

Sorry about that. Wrote in a rush.

> I've come up with the following for the problems I understand, but I'm
> sure it could do with a bit more prodding.
[...]

Thanks. That seems to do the trick.

May I knitpick:

~$ ''() echo X "$@"
~$ zargs 1 2 -- ''
1 2
~$ zargs 1 2 -- '' ''
X  1 2

--- zargs.old   2012-04-12 10:26:20.658633028 +0100
+++ /usr/share/zsh/functions/Misc/zargs 2012-04-12 10:27:20.709077765 +0100
@@ -174,7 +174,7 @@
 else set -- "${(@)argv[1,end-1]}"
 fi

-if [[ -n $command ]]
+if (($#command))
 then (( c = $#command - 1 ))
 else command=( print -r -- )
 fi


-- 
Stephane

Re: Problems with zargs (Was: xargs should be a builtin)

[Peter Stephenson]

On Thu, 12 Apr 2012 10:28:22 +0100
Stephane Chazelas <stephane.chazelas@gmail.com> wrote:
> --- zargs.old   2012-04-12 10:26:20.658633028 +0100
> +++ /usr/share/zsh/functions/Misc/zargs 2012-04-12 10:27:20.709077765 +0100
> @@ -174,7 +174,7 @@
>  else set -- "${(@)argv[1,end-1]}"
>  fi
> 
> -if [[ -n $command ]]
> +if (($#command))
>  then (( c = $#command - 1 ))
>  else command=( print -r -- )
>  fi

Thanks, I've committed it with that.

-- 
Peter Stephenson <p.w.stephenson@ntlworld.com>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/

Re: Problems with zargs (Was: xargs should be a builtin)

[Bart Schaefer]

On Apr 11, 11:06am, Stephane Chazelas wrote:
}
} By the way, there seems to be some issues with zargs:
}  
} ~$ zargs a b '' -- print -rl
} a
} b
} ~$ zargs a -- print -rl ''
} a

Hmm, empty strings are being collapsed out of $argv[end+1,-1] when it
is assigned.  I'm not remembering whether that's expected or something
new.  Patch below, though it probably needs some more test cases.

} ~$ zargs -e a '' print -rl
} a print -rl
} ~$ zargs --eof= a '' print -rl
} a

This is actually the expected behavior.  "zargs --help":

--eof[=eof-str], -e[eof-str]
    Change the end-of-input-args string from "--" to eof-str.  If
    given as --eof=, an empty argument is the end; as --eof or -e,
    with no (or an empty) eof-str, all arguments are input-args.


Index: Functions/Misc/zargs
===================================================================
retrieving revision 1.6
diff -c -r1.6 zargs
--- zargs	20 Dec 2011 17:13:38 -0000	1.6
+++ zargs	12 Apr 2012 22:48:19 -0000
@@ -167,11 +167,11 @@
 elif (( $#eof )); then end=$argv[(i)${eof##-(e|-eof=)}]
 else end=$argv[(i)--]
 fi
-local -a args call command; command=( ${argv[end+1,-1]} )
+local -a args call command; command=( "${(@)argv[end+1,-1]}" )
 
 if (( $opts[(I)-(null|0)] ))
-then set -- ${(ps:\000:)argv[1,end-1]}
-else set -- $argv[1,end-1]
+then set -- "${(@ps:\000:)argv[1,end-1]}"
+else set -- "${(@)argv[1,end-1]}"
 fi
 
 if [[ -n $command ]]
@@ -187,7 +187,7 @@
     then print -u2 -r -- "$call"
     fi
     eval "{
-	\$call
+	${(@qq)call}
     } $bg"'
 local ret=0 analyze='
     case $? in
@@ -205,7 +205,7 @@
     if (( $opts[(I)-(-no-run-if-empty|r)] ))
     then return 0
     else
-	call=($command)
+	call=( "${(@)command}" )
 	# Use "repeat" here so "continue" won't complain.
 	repeat 1; do eval "$execute ; $analyze"; done
 	return $ret
@@ -275,11 +275,11 @@
 	((ARGC)) || break
 	for (( end=l; end && ${(c)#argv[1,end]} > s; end/=2 )) { }
 	(( end > n && ( end = n ) ))
-	args=( $argv[1,end] )
+	args=( "${(@)argv[1,end]}" )
 	shift $((end > ARGC ? ARGC : end))
 	if (( $#i ))
-	then call=( ${command/$i/$args} )
-	else call=( $command $args )
+	then call=( "${(@)command/$i/$args}" )
+	else call=( "${(@)command}" "${(@)args}" )
 	fi
 	if (( ${(c)#call} > s ))
 	then

Re: Problems with zargs (Was: xargs should be a builtin)

[Bart Schaefer]

On Apr 13,  8:13pm, Peter Stephenson wrote:
} Subject: Re: Problems with zargs (Was: xargs should be a builtin)
}
} On Fri, 13 Apr 2012 08:43:50 -0700
} Bart Schaefer <schaefer@brasslantern.com> wrote:
} > One concern I have is that this may have changed behavior with respect
} > to aliases.  Does the first word of $call need to be unquoted?
} 
} You're probably right that it's changed the behaviour.  I'm not sure if
} it was ever clear that aliases would be expanded, but there's no reason
} not to restore it.

I've just checked this against a few older versions of the shell and it
appears that aliases were never expanded.  So we can either leave it as
it is, or change it to allow aliases in the command position ... but
there is no way I can see to allow *global* aliases to expand without
breaking quoting of the rest of the arguments.

So perhaps the status quo is best maintained.

-- 
Barton E. Schaefer