dp_objectCreateProc, dp_objectExists, dp_objectFree, dp_objectConfigure, dp_objectSlot, dp_objectSlotSet, dp_objectSlotAppend, dp_objectSlots - dp_object manipulation using Tcl scripting
dp_objectCreateProc class object dp_objectExists object dp_objectSlots object dp_objectFree object dp_objectSlot object slot dp_objectSlotSet object slot value dp_objectSlotAppend object slot value dp_objectConfigure class object options
A procedural object is usually implemented in C (e.g., as a C struct) for speed but has a Tcl access interface. For example, Tk implements its widget classes in C but provides Tcl interfaces to access those widgets. Tk uses a procedure to represent each widget instance.
The first argument of one of these procedural objects is a method selector. In other words, if object is the name of a procedural object:
object method ?args ...?If you use the utility procedures described in this man page to implement a procedural object, that object will have a class and may have slots. The class of the object determines what methods the object will respond to. No class inheritance is supported. dp_objectCreateProc class object
This command creates a new Tcl procedure to represent a new object. The new procedure will have the name object and have the given class.
dp_objectExists objectThis command returns 1 if a procedural object named object exists in the interpreter and returns 0 otherwise.
dp_objectFree objectThis command frees up the resources associated with the object, which should have been created with dp_objectCreateProc. After using dp_objectFree on an object, no more references to that object or its slots should be made.
dp_objectSlots objectThis command returns a list of the slots of the procedural object, which should have been created with dp_objectCreateProc.
dp_objectSlot object slotThis command returns the value of a slot of the procedural object, which should have been created with dp_objectCreateProc.
dp_objectSlotSet object slot valueThis command sets the value of a slot of the object, which should have been created with dp_objectCreateProc. If slot is not yet a slot of the object, this command will make slot a slot of the object. Thus, slots can be dynamically added to objects created using dp_objectCreateProc. A slot may not be an array.
dp_objectSlotAppend object slot valueThis command uses lappend to append the given value to the current value of the slot of the object, which should have been created with dp_objectCreateProc. If slot is not yet a slot of the object, this command will make slot a slot of the object. Thus, slots can be dynamically added to objects created using dp_objectCreateProc.
dp_objectConfigure class object ?options?This command provides a Tk "configure" style of slot access for the procedural object, which should have been created using dp_objectCreateProc. (See example usage below.) The argument class should be the class of the object. The optional options argument can be used in the following three formats:
dp_objectConfigure class object ?-slot? dp_objectConfigure class object ?-slot val -slot val ...? dp_objectConfigure class objectThe first format of dp_objectConfigure retrieves the configuration entry for a given slot. A configuration entry for a slot is a triplet of the format of {-slot default value}, where -slot is the slot name prepended with a hyphen, default is the default value for the slot, and value is the current value of the slot. (Note that this configuration entry format for slots is different than the configuration entry format of Tk widget options.)
The second format of dp_objectConfigure sets the current values of several slots of an object.
The third format of dp_objectConfigure retrieves the configuration entries of all the slots of the object.
Note that to use dp_objectConfigure, you must prepend a hyphen ('-') to each slot name. (e.g., "slot" becomes "-slot".) This was designed for pseudo-compatability with the Tk style of widget option configuration, since widget options in Tk are all prefixed with a '-'. Also, any slot names, slot, should be fully specified and not abbreviated.
The command dp_objectCreateProc creates a new Tcl procedure whose name is object to represent a new procedural object. You may invoke various methods on the procedural object, using the following general form:
object method ?arg0 arg1 ...?The method argument and the class of the object determine the method invoked. Methods for classes are specified using the following form:
proc class.method {self arg0 ... argN} {
...method body...
}
The first argument self is required in the method specification.
The self argument is set to the name of the object that the
method will get called upon. The following is a simple example
of using the above commands to create a procedural object using
Tcl scripting only:
# Define point creator.
#
proc makePoint {aPoint args} {
eval dp_objectCreateProc point $aPoint;
dp_objectSlotSet $aPoint x 0;
dp_objectSlotSet $aPoint y 0;
eval $aPoint configure $args
return $aPoint;
}
# Define methods of point class.
#
proc point.configure {aPoint args} {
eval dp_objectConfigure point $aPoint $args;
}
proc point.slot-value {aPoint slot} {
dp_objectSlot $aPoint $slot;
}
proc point.destroy {aPoint slot} {
dp_objectFree $aPoint $slot;
}
proc point.draw {aPoint} {
set x [dp_objectSlot $aPoint x];
set y [dp_objectSlot $aPoint y];
dot $x $y;
}
# Instatiate a point and test it out.
#
makePoint p; # Makes the point
p configure -x 10 -y 20; # sets the value to (10,20)
p configure -x; # returns {-x {} 10}
p configure; # returns {{-x {} 10} {-y {} 20}}
p slot-value x; # returns 10
p draw; # calls "dot 10 20"
dp_objectExists p; # returns 1
dp_objectExists p1; # returns 0
p destroy; # destroys the object