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 BOOK Tcl/Tk Tools: contains an out of date tutorial for itcl.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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Whether a method occuring in the list is actually called or not will depend on preceding methods passing on the invocation via the next command. It becomes VERY easy to write clear, concise code. The returned list contains two interesting elements: The destructor method definition differs from other methods in that it only has a single tutotial – the ircl to be run.

We will now look at another mechanism to extend or change the behaviour of classes and objects – mixins. Instead of mixing our EFT class into CheckingAccountwe could have thtorial it a superclass and used multiple inheritance instead.

Creating a class Classes are created in TclOO using the oo:: Rather, the constructor method is automatically run when an object is created.

As seen above, the self filter command returns a list of three items: Classes and objects can override the default implementation method to take some other action instead. Obj81 saving account data to database. So the deposit method we saw earlier calls the UpdateBalance method as:.


It does not affect methods defined in the class so the original UpdateBalance will still be in place and will no longer be overridden. Imagine our banking system had the requirement that individual accounts can be frozen based on an order from the tax authorities. Many times, the filter method needs to know what method the caller is actually trying to invoke. Defining data members In our simple example, the state for an account object includes jtcl account number that uniquely identifies it and the current balance.

Just like the rest of Tcl, TclOO offers tuhorial and comprehensive introspection capabilities. It then runs the first implementation in this list. This is a draft chapter from the book The Tcl Programming Languagenow available in print and electronic form from Amazon, Gumroad igcl others.

As you can see, we have the same behaviour as before. Method definitions can be deleted at any time with the deletemethod command inside a class definition script. Note that modifying the class definition in any manner, in this case adding a mixin, also impacts existing objects of that class.

Tcl/Tk Tutorial

Notice that the EFT class does not really know anything about accounts. Views Read Edit View history.

Method chain order For the exact search order and construction of this method chain, see the reference documentation of the next command.


For example, the state contained in an object representing a bank account would include items such as the current balance and account number.

Accessing data members Data members are not directly accessible from outside the object. The actual functionality is immaterial but it is intended futorial be fairly general purpose for example, logging or tracing and mixable into any class. ClassWithOneArg with a single argument Constructing:: You can optionally specify a pattern argument in which case only objects whose names match the pattern using the rules of the string match command are returned.

itcl – object-oriented extensions to Tcl – Linux Man Pages (n)

Any operation on a destroyed object will naturally result in an error. Overridden base class method Method defined in derived class Check facility not available for savings.

For example, either oo:: AccountNumber and Balance are then visible within all methods of the class and can be referenced there without any qualifiers or declarations. Ever since its introduction in the yeariTcl or incr Tcl has gone on to turorial huge popularity among the Tcl Tk enthusiasts, and their development community.