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Release of TclOO Version 1.0.4

This officially corresponds to the version of TclOO that is included with Tcl 8.6.5, except for features (notably coroutine support and bytecode compilation of some commands) that require the 8.6 runtime.

TclOO: An Object System for Tcl

TclOO is an object system for Tcl that has been designed to provide high performance while still allowing as much flexibility as possible, and to be a core for other object systems. It supports a single-rooted class-based object system where classes are themselves subclassable objects, with multiple inheritance, mixins, procedure-like and forwarded methods, filter methods, dynamic reconfiguration, etc.

It does not come with a large class library, and it does not force its use upon user scripts. Some of the packages in Tcllib use TclOO, but these may be dependent on other Tcl 8.6 features.

The heritage of TclOO can be traced back to a number of other object systems, notably including XOTcl, incr Tcl, and Snit. It also draws on experience with object systems in other languages like C++, Java and Ruby (despite being somewhat different from each of them).

Changes in TclOO 1.0.4

  • TIP #436 was implemented, which makes info object isa not produce errors when presented with non-objects.

  • Various bugs in class destruction were addressed.

For a full description of all changes, see:

Note that there were no meaningful changes in 1.0.3.


TclOO 1.0.4 uses the TEA3 build system. These instructions are known to work on Linux, OSX and Windows (with msys installed).

  1. Make sure you have a source distribution of Tcl 8.5 somewhere; you will need it to build TclOO. (Note that this functionality is incorporated directly into Tcl 8.6; you do not need this package with that version.)

  2. Run the configure shell script in this directory. You may well want to use the --with-tcl option to tell the script where to find Tcl's build descriptor. Using the --prefix option to specify where to install the built version is also often useful.

  3. Run 'make'.

  4. Run 'make test'. There should be no test failures, but some memory stress tests are not run under normal conditions as they require a special build of Tcl.

  5. Run 'make install'. You might need to get elevated privileges to do this (e.g. by using 'sudo') to install in a shared area.


Please file bug reports, feature requests and patches on under the Tcl package. To ensure attention from the relevant maintainer, please use "35. TclOO Package" for the Category field. Remember, it is better to file a bug report twice than not at all!

Basic Usage of TclOO

Adding up values with TclOO:

oo::class create summation {
    variable v
    constructor {} {
        set v 0
    method add x {
        incr v $x
    method value {} {
        return $v
    destructor {
        puts "Ended with value $v"
set sum [summation new]
puts "Start with [$sum value]"
for {set i 1} {$i <= 10} {incr i} {
    puts "Add $i to get [$sum add $i]"
summation destroy

Toasting bread with events and TclOO:

oo::class create Toaster {
    variable toasting time
    constructor {toastingTime} {
        set time $toastingTime
        set toasting ""
    method toast {breadProduct} {
        if {$toasting ne ""} {
            error "already toasting something"
        set toasting [after $time [namespace code [list \
                my Toasted $breadProduct]]]
        puts "toasting $breadProduct for you"
    method Toasted {breadProduct} {
        puts "toasted the $breadProduct"
        set toasting ""
    destructor {
        after cancel $toasting

Toaster create quickToaster 30000 ;  # 30 seconds only
quickToaster toast crumpet

after 40000 {set done ok}
vwait done ;                         # Run the event loop

quickToaster destroy ;               # Delete the object

Compatibility Warnings

Names of classes, methods or variables that begin with a hyphen can now cause issues with some definitions (i.e., they are reserved to slotted operations). The fix is to precede the name with a "--" argument in the problem definition; see the oo::define documentation for the affected definitions.

Method names that are proper multi-element lists are reserved for future functionality.


Tcl OO Package (for Tcl 8.5, integrated in 8.6). (Mirror of







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