Documentation generated from fossil trunk
oo::class -
class of all classes
package require TclOO oo::class method ?arg ...?
oo::object -> oo::class
Classes are objects that can manufacture other objects according to a pattern stored in the factory object (the class). An instance of the class is created by calling one of the class's factory methods, typically either create if an explicit name is being given, or new if an arbitrary unique name is to be automatically selected.
The oo::class class is the class of all classes; every class is an instance of this class, which is consequently an instance of itself. This class is a subclass of oo::object, so every class is also an object. Additional metaclasses (i.e., classes of classes) can be defined if necessary by subclassing oo::class. Note that the oo::class object hides the new method on itself, so new classes should always be made using the create method.
The constructor of the oo::class class takes an optional argument which, if present, is sent to the oo::define command (along with the name of the newly-created class) to allow the class to be conveniently configured at creation time.
The oo::class class does not define an explicit destructor. However, when a class is destroyed, all its subclasses and instances are also destroyed, along with all objects that it has been mixed into.
Note that this method is not exported by the oo::class object itself, so classes should not be created using this method.
The oo::class class supports the following non-exported methods:
This example defines a simple class hierarchy and creates a new instance of it. It then invokes a method of the object before destroying the hierarchy and showing that the destruction is transitive.
oo::class create fruit { method eat {} { puts "yummy!" } } oo::class create banana { superclass fruit constructor {} { my variable peeled set peeled 0 } method peel {} { my variable peeled set peeled 1 puts "skin now off" } method edible? {} { my variable peeled return $peeled } method eat {} { if {![my edible?]} { my peel } next } } set b [banana new] $b eat -> prints "skin now off" and "yummy!" fruit destroy $b eat -> error "unknown command"