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 BOOK Tcl/Tk Tools: contains an out of date tutorial for itcl.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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Object Oriented Programming in Tcl
These tasks are performed through the special methods named constructor and destructor. Introspection There are three things extremely hard: This creates a new class Account that can be used to create objects representing bank accounts.
That leaves the question of multiple inheritance. This information can be obtained with the self next command from within a method context. Moreover, since Tcl is a dynamic language, we would have to make sure we do that any time new methods were defined for the object or any ancestor and mixin.
When the script passed to oo:: The intention behind inheritance is to model is-a relationships.
If a derived class does not define a constructor, as is true for the CheckingAccount class, the base class constructor is invoked when the object is created.
Note this is not the same as the class the object belongs to as the example below shows. Inheritance implies an is-a relationship between classes. The object would respond to messages to deposit ihcl withdraw funds.
This can be useful for example when namespaces are used to segregate icl.
itcl (n) – Linux Man Pages
Let us rework our previous example. This is an artifact of the implementation and this should not be relied on.
Derived method method m:: It was one of the earliest Tcl-based OO extensions to be widely used. Most of the special commands like itfl and variable that we have seen used inside oo:: Earlier we looked at the use of inheritance to extend a class.
Another point about method definitions concerns method visibility. Having defined our model, we can now begin operation of our bank to illustrate how objects are used.
Filter methods offer a easier solution. An Account object responds to requests to get the current balance and to requests for depositing and withdrawing funds.
So for example if we had a facility for electronic bill presentment implemented as a mixin class BillPaywe could have added it along with EFT as a mixin in a single statement. History Between and there were over a dozen OO extensions for Tcl: The new method generates a name for the created object. The filter method may choose to pass on the target method result, some transformed version of it, or something else entirely.
For these reasons, mixins seemed a better choice in our design aside from the fact that we needed some example to illustrate mixins.
About iTcl or incr Tcl
tutorail Most of the example code in this chapter is based on a framework for modeling banks. Thus in our banking example, we may define itxl classes representing savings accounts and checking accounts, each inheriting from the base account and therefore having a balance and methods for deposits and withdrawal. You can help Wikipedia by expanding it.
Destructors behave in a similar fashion. The author uses mixed case for data members to avoid conflicts with names of method arguments and local variables. This is detail as it maintains the same itcl programmer interface.
itcl – object-oriented extensions to Tcl – Linux Man Pages (n)
How would we do this? Naturally that fails because it is not a checking account. Just like in that case a method takes an arbitrary number of arguments including a variable number of trailing arguments collected as the args variable.
Let us illustrate with ktcl banking example. Scripting languages Dynamically typed programming languages Tcl programming language family software Programming language topic stubs. Notice that although the next method in the method chain is printed out, it does not actually get invoked because the m method in Derived no longer calls next. One of the knocks against Tcl in its early days tutorila that it did not support object oriented programming.
It was intended to make programmers used to that language feel at home.