if 0 {[Richard Suchenwirth] 2003-11-04 - A colleague asked me for a skeleton for simple OO in Tcl, and said I should wikify it too ;) - so here it is. It basically has only one "singleton class" ''filetbl'', and mixes generic and specific code - I marked the specific parts, so you can put your own content there. But it's simple, and maybe interesting to read.
}
 namespace eval filetbl {
    variable n 0
 }

#---------------------------------- Constructor
 proc filetbl::create filename {
    variable n
    set fp [open $filename]           ;# specific
    set tbl "put your data here - $n" ;# specific

    namespace eval [incr n] \
	[list variable filename $filename fp $fp tbl $tbl] ;# variables specific
    set self [namespace current]
    interp alias {} ${self}::$n {} ${self}::dispatch $n
    return ${self}::$n
 }
#---------------------------------- Method dispatcher
 proc filetbl::dispatch {this cmd args} {
    eval $cmd $this $args
 }

#-----------------------------------Destructor
 proc filetbl::delete this {
    close [set ${this}::fp] ;# specific
    namespace delete $this
    interp alias {} [namespace current]::$this {}
 }
#------------------------------- Further problem-specific methods come here:
 proc filetbl::test {this args} {
    puts [list hello $args]
    puts "tbl= [set ${this}::tbl]"
 }

#------------------------------- Self-test
 if {[file tail [info script]] eq [file tail $argv0]} {

    set ft [filetbl::create [info script]]
    $ft test hello world ;# == filetbl::test $ft hello world
    $ft delete

 }

----
[Category Object Orientation] - [Arts and crafts of Tcl-Tk programming]