# Listing of doc/example-scripts/tk-spread.tcl

A small Spreadsheet implementation, originally developed by Richard Suchenwirth in plain Tcl (see http://wiki.tcl.tk/1287). The spreadsheet was rewritten in an object oriented manner as a design study in NX by Gustaf Neumann in May 2011.

    package require Tk
    package require nx::trait

     ##############################################################################
     # Class SpreadSheet
     #
     # The SpreadSheet computes simply totals for rows and columns.
     ##############################################################################
     nx::Class create SpreadSheet {
       #
       # The following attributes can be used for configuring the
       # spreadsheet.
       #
       :property {rows:integer 3}
       :property {cols:integer 2}
       :property {width:integer 8}

       #
       # If no widget is provided, use the name of the object as widget
       # name.
       #
       :property {widget ".[namespace tail [self]]"}

       #
       # Use the nx callback trait
       #
       :require trait nx::trait::callback

       #
       # The method "cell" hides the internal respresentation and sets a
       # cell to a value.
       #
       :method cell {pair value} {
         set :data($pair) $value
       }

       #
       # The constructor builds the SpreadSheet matrix via multiple text
       # entry fields.
       #
       :method init {} {
         set :last ${:rows},${:cols}  ;# keep grand total field
         trace var [:bindvar data] w [:callback redo]
         frame ${:widget}
         for {set y 0} {$y <= ${:rows}} {incr y} {
           set row [list]
           for {set x 0} {$x <= ${:cols}} {incr x} {
             set e [entry ${:widget}.$y,$x -width ${:width} \
                        -textvar [:bindvar data($y,$x)] -just right]
             if {$x==${:cols} || $y==${:rows}} {
               $e config -state disabled -background grey -relief flat
             }
             lappend row $e
           }
           grid {*}$row -sticky news
         }
         $e config -relief solid
       }

       #
       # The method "redo" is triggered via the updates in the cells
       #
       :public method redo {varname el op} {
         if {$el ne ${:last}} {
           lassign [split $el ,] y x
           if {$x ne ""} {
             :sum $y,* $y,${:cols}
             :sum *,$x ${:rows},$x
           } ;# otherwise 'el' was not a cell index
         }   ;# prevent endless recalculation of grand total
       }

       #
       # The method "sum" adds the values matched by pattern (typically a
       # row or column) and sets finally the target column with the total
       #
       :method sum {pat target} {
         set sum 0
         set total "" ;# default if no addition succeeds
         foreach {i value} [array get :data $pat] {
           if {$i != $target} {
             if {[string is double -strict $value]} {
               set total [set sum [expr {$sum + $value}]]
             }
           }
         }
         :cell $target $total
       }
     }

Build spreadsheet "x"

    SpreadSheet create x {
       # populate with some values
       :cell 0,0 Spread1
       :cell 1,0 47
       :cell 2,1 11
     }

Build spreadsheet "y"

    SpreadSheet create y -rows 4 -cols 4 {
       :cell 0,0 Spread2
       :cell 1,0 12
       :cell 2,2 22
     }

Pack the spreadsheets into one pane

    pack [x cget -widget] [y cget -widget] -fill both