examples/functions/autoload.v3

   1 #From: Mark Kennedy <mark.t.kennedy@gmail.com> (<mtk@ny.ubs.com>)
   2 #Message-ID: <35E2B899.63A02DF5@ny.ubs.com>
   3 #Date: Tue, 25 Aug 1998 09:14:01 -0400
   4 #To: chet@nike.ins.cwru.edu
   5 #Subject: a newer version of the ksh-style 'autoload'
   6
   7 #enclosed you'll find 'autoload.v3',  a version of the autoloader
   8 #that emulates the ksh semantics of delaying the resolution (and loading) of the function
   9 #until its first use.  i took the liberty of simplifying the code a bit although it still uses the
  10 #same functional breakdown.  i recently went through the exercise of converting
  11 #my ksh-based environment to bash (a very, very pleasant experience)
  12 #and this popped out.
  13
  14 # the psuedo-ksh autoloader.
  15
  16 # The first cut of this was by Bill Trost, trost@reed.bitnet.
  17 # The second cut came from Chet Ramey, chet@ins.CWRU.Edu
  18 # The third cut came from Mark Kennedy, mtk@ny.ubs.com.  1998/08/25
  19
  20 unset _AUTOLOADS
  21
  22 _aload()
  23 {
  24     local func
  25     for func; do
  26         eval $func '()
  27                 {
  28                     local f=$(_autoload_resolve '$func')
  29                     if [[ $f ]]; then
  30                         . $f
  31                         '$func' "$@"
  32                         return $?
  33                     else
  34                         return 1
  35                     fi
  36                 }'
  37         _autoload_addlist $func
  38     done
  39 }
  40
  41 _autoload_addlist()
  42 {
  43         local func
  44
  45         for func in ${_AUTOLOADS[@]}; do
  46             [[ $func = "$1" ]] && return
  47         done
  48
  49         _AUTOLOADS[${#_AUTOLOADS[@]}]=$1
  50 }
  51
  52 _autoload_dump()
  53 {
  54     local func
  55
  56     for func in ${_AUTOLOADS[@]}; do
  57         [[ $1 ]] && echo -n "autoload "
  58         echo $func
  59     done
  60 }
  61
  62 _autoload_remove_one()
  63 {
  64     local func
  65     local -a NEW_AUTOLOADS
  66
  67     for func in ${_AUTOLOADS[@]}; do
  68         [[ $func != "$1" ]] && NEW_AUTOLOADS[${#NEW_AUTOLOADS[@]}]=$func
  69     done
  70
  71     _AUTOLOADS=( ${NEW_AUTOLOADS[@]} )
  72 }
  73
  74 _autoload_remove()
  75 {
  76     local victim func
  77
  78     for victim; do
  79         for func in ${_AUTOLOADS[@]}; do
  80             [[ $victim = "$func" ]] && unset -f $func && continue 2
  81         done
  82         echo "autoload: $func: not an autoloaded function" >&2
  83     done
  84
  85     for func; do
  86             _autoload_remove_one $func
  87     done
  88 }
  89
  90 _autoload_resolve()
  91 {
  92     if [[ ! "$FPATH" ]]; then
  93             echo "autoload: FPATH not set or null" >&2
  94             return
  95     fi
  96
  97     local p
  98
  99     for p in $( (IFS=':'; set -- ${FPATH}; echo "$@") ); do
 100         p=${p:-.}
 101         if [ -f $p/$1 ]; then echo $p/$1; return; fi
 102     done
 103
 104     echo "autoload: $1: function source file not found" >&2
 105 }
 106
 107 autoload()
 108 {
 109     if (( $# == 0 )) ; then _autoload_dump; return; fi
 110
 111     local opt OPTIND
 112
 113     while getopts pu opt
 114     do
 115         case $opt in
 116             p) _autoload_dump printable; return;;
 117             u) shift $((OPTIND-1)); _autoload_remove "$@"; return;;
 118             *) echo "autoload: usage: autoload [-pu] [function ...]" >&2; return;;
 119         esac
 120     done
 121
 122     shift $(($OPTIND-1))
 123
 124     _aload "$@"
 125 }