Re: win32 short name and IFS='~'

[Naofumi Yasufuku]

At Thu, 17 Apr 2003 14:49:45 -0500,
Boehne, Robert wrote:
> 
> Naofumi,
> 
> #! /bin/sh
> # How about ditching use of IFS totally in favor of a series of commands
> # to be executed.  For example, we currently use
> show="echo"
> run=
> 
> test_cmds='echo "do command one"~echo "do command two"~echo "do command 
> three"'
> 
> #then, rather than do this:
>       save_ifs="$IFS"; IFS='~'
>       for cmd in $test_cmds; do
>         IFS="$save_ifs"
>         $show "$cmd"
>         $run eval "$cmd" || exit $?
>       done
>       IFS="$save_ifs"
> 
> # suppose we used
> archive_cmds_1='echo "do command one"'
> archive_cmds_2='echo "do command two"'
> archive_cmds_3='echo "do command three"'
> archvie_cmds_max=3
> 
> echo " We would do something like this: "
> n=0
> cmd=
> while true; do
>   n=`expr $n + 1`
>   cmd="\$archive_cmds_$n"
>   if test $n -le $archvie_cmds_max ; then
>     $show "$cmd"
>     $run eval "$cmd" || exit $?
>   else
>     break;
>   fi
> done
> 
> The real trick to making this work is to get the
> shell quoting exactly the same so that we can simply
> take current command (~ separated lists) and convert them to
> a series without changing the quoting.
> The script above doesn't do this :(  but it can be used
> by all to attempt to figure out the right quoting to
> have the desired result.  This type of solution has
> the distinct advantage of not using any other character
> for IFS, and so cannot ever clash with characters in
> commands.
> I would also encourage the use of shell functions to
> simplify this, or any other bit of libtool for that matter.
> 

Robert,

The nature of this '~'-IFS problem is when command variables should be
expanded.
"first expand, then separate" or "first separate, then expand".

  #! /bin/sh
  # "first expand, then separate" (current libtool)
  
  archive_cmds="\$command_one \$deplibs~\$command_two"
  
  command_one='gcc -shared ...'
  command_two='echo "do command two"'

  deplibs='-L/foo~bar/lib -lbaz'
  
  eval cmds=\"$archive_cmds\"  # *** first expand archive_cmds ***
  
  # Execute for earch field
  save_ifs="$IFS"; IFS='~'
  for cmd in $cmds; do         # *** then separate ***
    IFS="$save_ifs"
    $show "$cmd"
    $run eval "$cmd" || exit $?
  done
  IFS="$save_ifs"

$cmds will be separated at wrong point (-L/foo; bar/lib -lbaz).

  #! /bin/sh
  # "first separate, then expand"
  
  archive_cmds="\$command_one \$deplibs~\$command_two"
  
  command_one='gcc -shared ...'
  command_two='echo "do command two"'

  deplibs='-L/foo~bar/lib -lbaz'
  
  # Execute for earch field
  save_ifs="$IFS"; IFS='~'
  for cmd in $archive_cmds; do  # *** first separate ***
    IFS="$save_ifs"
    eval cmd=\"$cmd\"           # *** then expand cmd ***
    $show "$cmd"
    $run eval "$cmd" || exit $?
  done
  IFS="$save_ifs"

This is the solution that I suggested first. $archive_cmds will be
separated at right point. We don't need to be concerned about '~' in
$archive_cmds.

  #! /bin/sh
  # The solution Robert suggested

  archive_cmds="\$command_one \$deplibs~\$command_two"
  
  command_one='gcc -shared ...'
  command_two='echo "do command two"'

  deplibs='-L/foo~bar/lib -lbaz'
  
  # *** Expand archive_cmds ***
  eval cmds=\"$archive_cmds\"
  
  # Convert to a series (will fail :-<)
  archive_cmds_1='gcc -shared ... -L/foo'
  archive_cmds_2='bar/lib -lbaz'
  archive_cmds_3='echo "do command two"'
  archvie_cmds_max=3

  n=0
  cmd=
  while true; do
    n=`expr $n + 1`
    cmd="\$archive_cmds_$n"
    if test $n -le $archvie_cmds_max ; then
      $show "$cmd"
      $run eval "$cmd" || exit $?
    else
      break;
    fi
  done

It will be the same result of current libtool.

Regards,
--Naofumi