oo::copy — create copies of objects and classes
package require tcl::oo
oo::copy sourceObject ?targetObject? ?targetNamespace?
The oo::copy command creates a copy of an object or class. It takes the
name of the object or class to be copied, sourceObject, and optionally
the name of the object or class to create, targetObject, which will be
resolved relative to the current namespace if not an absolute qualified name
and
targetNamespace which is the name of the namespace that will hold the
internal state of the object (my command, etc.); it must not
refer to an existing namespace.
If either targetObject or targetNamespace is omitted or is given
as the empty string, a new name is chosen. Names, unless specified, are
chosen with the same algorithm used by the new method of
oo::class.
The copied object will be of the same class as the source object, and will have
all its per-object methods copied. If it is a class, it will also have all the
class methods in the class copied, but it will not have any of its instances
copied.
After the targetObject has been created and all definitions of its
configuration (e.g., methods, filters, mixins) copied, the <cloned>
method of targetObject will be invoked, to allow for customization of
the created object such as installing related variable traces. The only
argument given will be sourceObject. The default implementation of this
method (in oo::object) just copies the procedures and variables in the
namespace of sourceObject to the namespace of targetObject. If
this method call does not return a result that is successful (i.e., an error
or other kind of exception) then the targetObject will be deleted and an
error returned.
The result of the oo::copy command will be the fully-qualified name of
the new object or class.
This example creates an object, copies it, modifies the source object, and
then demonstrates that the copied object is indeed a copy.
oo::object create src
oo::objdefine src method msg {} {puts foo}
oo::copy src dst
oo::objdefine src method msg {} {puts bar}
src msg → prints "bar"
dst msg → prints "foo"
oo::class, oo::define, oo::object
clone, copy, duplication, object
Copyright © 2007 Donal K. Fellows