ITCL TUTORIAL PDF
Abbreviated form of incr Tcl, iTcl is the term used for referring to the object- oriented extensions meant for Tcl programming language. Let’s learn more about . The name is often written as “itcl” as that contains no metacharacters (i.e., space or brackets). BOOK Tcl/Tk Tools: contains an out of date tutorial for itcl. A more tutorial introduction is presented in the paper included with this distribution. See the class command for more details on creating and using classes.
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Retrieving the method chain The info class call command retrieves the method chain for a method. Defining a filter class The filter declaration need not occur in the same class that defines the filter method. The literature on the subject describes mix-ins in several different ways, often depending on language-specific capabilities.
Incr Tcl – Wikipedia
Don’t mess with the IRS, dude! As expected, the unknown methods, where defined, are called.
What will the method chain for method m look like? Inheritance refers to the ability of a derived class also refered to as a subclass to specialize a class – called its base class or superclass tuyorial by extending or modifying its behaviour. In the real world, it would be a checkbox on a account opening form for a checking account. The superclass command in the class definition establishes that SavingsAccount and CheckingAccount inherit from Account.
Object identity Who in the world am I? Our filter method is not exported because it starts with an upper-case letter.
About iTcl or incr Tcl
Notice that the class definition of UpdateBalance was not lost in the process of adding and deleting the object-specific method. Methods in derived classes Methods available in the base class are available in derived classes as well. The iTcl implementations exist both in the form of a standalone independent language having its own interpreter as well as a package which can be dynamically loaded by any Tcl application.
Monthly interest Pretend we are writing a check. You cannot use multiple inheritance to specialize individual objects in this manner. Let us go back to our banking model. So we come up with a new type of account, a Cash Management Account CMAwhich combines the features of the checking and brokerage accounts. Here we will simply illustrate with an example where we define a class hierarchy with multiple inheritance, mixins, filters and object-specific methods.
The unknown method is passed the name of the invoked method as its first argument followed by the arguments from the invocation call. You cannot claim ownership of the software; the authors and their institutions retain ownership, as described in the “license. In addition to supporting object-oriented programming. Introspecting filter contexts When a method is run as a filter, it is often useful for it to know the real target method being invoked.
Constructor and destructor method chains are only available through self callnot through info class call.
They need to be brought into scope with the my variable statement. Destroying classes A class, as we shall itc, later, is also an object and like all objects can be destroyed. Defining methods Having defined the data members, let us move on to defining the methods that comprise the behaviour of an Account object. Applications created with Tcl Tk have the ability of coming together with great ease.
A class is loosely speaking a template that defines the data items and methods collectively called members encapsulated by objects of a specific type. This is done with the command next which invokes the next method in the which in this case is the superclass method with the same name as the current method. Having defined the data members, let us move on to defining the methods that comprise the behaviour of an Account object.
Further we have mixins for both a class and directly into the object. Thus a checking account is a bank account and can be used at any place in the banking model where the behaviour associated with a bank account is expected. We will see these as we proceed with our example but for now note the use of my to refer to a method of the object in whose context the current method is running.
Modifying an existing class As we have seen in previous sections, you can incrementally modify a class using oo:: Destroying objects Objects in Tcl are not garbage itc, as in some other languages and have to be explicitly destroyed by calling their built-in destroy method. Enumerating methods The list of methods implemented by a class or object can be retrieved through info class methods and info object methods respectively.
Constructors and destructors There is one final thing we need to do before we can start banking operations and that is to provide some means to initialize an Account object when it is created and perform any required clean up when it is destroyed.
Inspecting method chains within method contexts Within a method context, the command self call returns more or less the same information for the current object as info object call. As discussed earlierwhen calling a method from another method in the same object contextiycl alias my is used to refer to ttorial current object. Let us see how all this works. No value judgement intended. You need to specify the -append option in that case. We have created an object of class Derived that inherits from two parent classes, all of which define a method m.
We can model this in our system using multiple inheritancewhere the corresponding class inherits from more than one parent class. AMGApril As you see, a method is defined in exactly the same manner as proc defines a Tcl procedure.