if 0 {[Richard Suchenwirth] 2005-03-16 - Here's a little experiment in [OO] using the [Jim] feature that procs and [lambda]s can have a "closure" (a set of static variables) associated. 

(Note that this code does not run on regular Tcl interpreters - use [Jim] instead!)

This way, the only physical location of an object is its lambda - rename it away as destructor. No namespaces needed (or possible in Jim ;^)}

#-- Here's a "constructor" the hard (bare-bones) way:
 proc Account args {
    lambda {method args} {{balance 0}} {eval Account'$method $args}
 }
if 0 {Alternatively, if you want to use more than one class, here's factoring out the generic part:}
    proc class {name instvars} {
	set     body [list lambda {method args} $instvars]
	lappend body "eval $name'\$method \$args"
	proc $name args $body
    }
#-- Let's re-create a first class, the usual bank account, with one instance variable:
 class Account {
    {balance 0}
 }
#-- Methods need to [upvar] the instance vars they need:

 proc Account'deposit amount {
    upvar 1 balance balance
    set balance [+ $balance $amount]
 }
 proc Account'see {} {
    upvar 1 balance balance
    set balance
 }
 proc Account'withdraw amount {
    upvar 1 balance balance
    if {($balance-$amount)<0} {error "can only withdraw $balance"}
    set balance [- $balance $amount]
    puts "now: [[self] see]"
 }
if 0 {"Who am I?" is a deep philosophical question. Inside methods, it's easily answered:}
 proc self {} {lindex [info level -2] 0}

if 0 {Now testing:
 set a [Account]
 puts a:$a
 $a deposit 100
 puts "deposit 100 -> [$a see]"
 $a withdraw 40
 puts [$a see]
 catch {$a withdraw 1000} res
 puts $res
shows on stdout
 a:<reference.<functio>.00000000000000000000>
 deposit 100 -> 100
 now: 60
 60
 can only withdraw 60

----
[SS] Very nice! It seems to me a very natural hack to try to implement objects via closures. Also your way to do the dispatch is impressive ;)
----
[Arts and crafts of Tcl-Tk programming] | 
[Category Object Orientation] | 
[Category Jim]
}