object(3tcl) TclOO Commands object(3tcl)
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NAME
oo::object - root class of the class hierarchy
SYNOPSIS
package require TclOO
oo::object method ?arg ...?
CLASS HIERARCHY
oo::object
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DESCRIPTION
The oo::object class is the root class of the object hierarchy; every
object is an instance of this class. Since classes are themselves ob-
jects, they are instances of this class too. Objects are always re-
ferred to by their name, and may be renamed while maintaining their
identity.
Instances of objects may be made with either the create or new methods
of the oo::object object itself, or by invoking those methods on any of
the subclass objects; see oo::class for more details. The configuration
of individual objects (i.e., instance-specific methods, mixed-in
classes, etc.) may be controlled with the oo::objdefine command.
Each object has a unique namespace associated with it, the instance
namespace. This namespace holds all the instance variables of the ob-
ject, and will be the current namespace whenever a method of the object
is invoked (including a method of the class of the object). When the
object is destroyed, its instance namespace is deleted. The instance
namespace contains the object's my command, which may be used to invoke
non-exported methods of the object or to create a reference to the ob-
ject for the purpose of invocation which persists across renamings of
the object.
CONSTRUCTOR
The oo::object class does not define an explicit constructor.
DESTRUCTOR
The oo::object class does not define an explicit destructor.
EXPORTED METHODS
The oo::object class supports the following exported methods:
obj destroy
This method destroys the object, obj, that it is invoked upon,
invoking any destructors on the object's class in the process.
It is equivalent to using rename to delete the object command.
The result of this method is always the empty string.
NON-EXPORTED METHODS
The oo::object class supports the following non-exported methods:
obj eval ?arg ...?
This method concatenates the arguments, arg, as if with concat,
and then evaluates the resulting script in the namespace that is
uniquely associated with obj, returning the result of the evalu-
ation.
obj unknown ?methodName? ?arg ...?
This method is called when an attempt to invoke the method
methodName on object obj fails. The arguments that the user sup-
plied to the method are given as arg arguments. If methodName │
is absent, the object was invoked with no method name at all (or │
any other arguments). The default implementation (i.e., the one
defined by the oo::object class) generates a suitable error, de-
tailing what methods the object supports given whether the ob-
ject was invoked by its public name or through the my command.
obj variable ?varName ...?
This method arranges for each variable called varName to be
linked from the object obj's unique namespace into the caller's
context. Thus, if it is invoked from inside a procedure then the
namespace variable in the object is linked to the local variable
in the procedure. Each varName argument must not have any name-
space separators in it. The result is the empty string.
obj varname varName
This method returns the globally qualified name of the variable
varName in the unique namespace for the object obj.
obj <cloned> sourceObjectName
This method is used by the oo::object command to copy the state │
of one object to another. It is responsible for copying the pro- │
cedures and variables of the namespace of the source object │
(sourceObjectName) to the current object. It does not copy any │
other types of commands or any traces on the variables; that can │
be added if desired by overriding this method in a subclass.
EXAMPLES
This example demonstrates basic use of an object.
set obj [oo::object new]
$obj foo → error "unknown method foo"
oo::objdefine $obj method foo {} {
my variable count
puts "bar[incr count]"
}
$obj foo → prints "bar1"
$obj foo → prints "bar2"
$obj variable count → error "unknown method variable"
$obj destroy
$obj foo → error "unknown command obj"
SEE ALSO
my(3tcl), oo::class(3tcl)
KEYWORDS
base class, class, object, root class
TclOO 0.1 object(3tcl)
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