scripts/chain.itcl

   1 class tlc::Chain {
   2         constructor {args} {}
   3         destructor {}
   4
   5         public {
   6                 variable id
   7                 variable name
   8                 variable parent
   9                 variable previous       ""
  10                 variable next           ""
  11
  12                 method new_previous {obj}
  13                 method new_next {obj}
  14                 method first_item {}
  15         }
  16 }
  17
  18
  19 body tlc::Chain::constructor {args} {
  20         eval configure $args
  21
  22         if {$previous != ""} {
  23                 set next        [$previous new_next $this]
  24                 if {$next != ""} {
  25                         $next new_previous $this
  26                 }
  27         }
  28 }
  29
  30
  31 body tlc::Chain::destructor {} {
  32         if {$next != ""} {
  33                 $next new_previous $previous
  34         }
  35         if {$previous != ""} {
  36                 $previous new_next $next
  37         }
  38 }
  39
  40
  41 body tlc::Chain::new_previous {obj} {
  42         set previous            $obj
  43 }
  44
  45
  46 body tlc::Chain::new_next {obj} {
  47         set old_next    $next
  48         set next                $obj
  49
  50         return $old_next
  51 }
  52
  53
  54 body tlc::Chain::first_item {} {
  55         if {$previous == ""} {
  56                 return $this
  57         } else {
  58                 return [$previous first_item]
  59         }
  60 }
  61
  62