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 BOOK Tcl/Tk Tools: contains an out of date tutorial for itcl.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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Igcl, such as balance in our example, have to be defined to allow callers to read and modify their values. In addition, the self command can be used for introspection of an object from inside a method context for that object.
Classes are created tjtorial TclOO using the oo:: Smith can withdraw money freely from his account. Practically nothing about tugorial class is sacred – you can add or delete methods, data members, change superclasses tutoria mixins, and so on.
Nevertheless, as we go along we will briefly describe some basic concepts for the benefit of the reader who really is completely unexposed to OO programming. Defining data members In our simple example, the state for an account object includes an account number that uniquely identifies it and the current balance. This became part of the Tcl 8. The returned list contains two interesting elements: If found, the lookup returns tutrial index into a function table that can then be invoked through the ComCall method.
For more information please see incrtcl. The home page is http: More often than not, creating a object of the class, often known as instantiating an object, is one of the duties of the class. We could have actually defined an unfreeze procedure instead of a unfreeze method as follows:.
It was one of the earliest Tcl-based OO extensions to be widely used. Its return value is a pair containing the declarer of the method and the target method name. Tutorixl class relationships The info class superclasses command returns the direct superclasses of a class. This circular and self-referential relationship between oo:: The final resultant code is much easier to comprehend and maintain.
Object Oriented Programming in Tcl
Therefore, after making the check we want to just pass on the request to the base class method icl not duplicate its code. Enumerating objects The info class instances command returns a list of objects belonging to the specified class.
The author uses mixed case for data members to avoid conflicts with names of method arguments and iycl variables. Accordingly we have a class corresponding to a brokerage account. Smith is suspected of being up to his old tricks again and we need to monitor his accounts and log all activity.
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. The properties and methods exported from a COM component are not always known beforehand and in fact can be dynamically modified.
They are not explicitly invoked by name. Retrieving method definitions To retrieve the definition of a specific method, use info class definition. Inspecting method chains within method contexts Within a method context, the command self call returns more or less the same otcl for the current object as info object call.
Working with objects Having defined our model, we can now begin operation of our bank to illustrate how objects are used.
Naturally that fails because it is not a checking account.
itcl (n) – Linux Man Pages
For example, suppose instead of logging every transaction as in our earlier example, we only wanted to log withdrawals. Filter methods Imagine Mr. The filter declaration need not occur in the same class tutoriao defines the filter method. Enumerating methods The list of methods implemented by a class or ittcl can be retrieved through info class methods and info object methods respectively. Multiple inheritance Imagine our bank is actually a full financial services firm that also provides stock trading services.
That leaves the question of multiple inheritance. Creating an object An object of a class is created by invoking one of two built-in methods on the class itself.
Since we want all checking accounts to have this facility, hutorial will add EFT to the CheckingAccount class as a mixin. The method context also makes available several commands – such as selfnext and my – which can only be called from within a method.
They do not have to be defined in which case TclOO will simply generate empty methods for them. The advantage of course is that defining a class allows a collection of additional behaviours to be abstracted and easily added to any class or object without repeating the code. We will not worry about how this is done but just assume some global procedures are available for the purpose.