Event Driven Programming

One of the reasons why Tcl is considered a highly powerful programming language is because of its event driven input/output model which permeates into almost everything ranging from graphic user interfaces (GUIs), networks, files and more. This lends a lot of credibility to the Tcl programming language, making it highly consistent, without the need of relying on the more complex add-on packages or mechanisms, which become a necessity in most languages.

When compared to other programming languages, dealing with asynchronous activities like GUI actions, data availability on sockets, files becoming readable and more become a matter of pure joy in Tcl. Other languages treat all such activities differently and require certain add-on packages or mechanisms for them. What sets Tcl apart are:

Its unified model - All Tcl Tk programs dealing with input/output operations have a single event loop as their main characteristic. Events get fired and Tcl callbacks get invoked when anything happens on the timers, GUI, sockets, files or other kinds of input sources.

There’s no need of threads for performing basic asynchronous input/output operations, and no add-on packages are needed for this functionality. In Tcl, all this is inbuilt and easy to comprehend. It’s all handled in a very consistent manner across the board.

Its callbacks - Callbacks become very easy with the ‘string’ model of Tcl. They can be any Tcl command by itself, an object invocation or a simple procedure call. There’s no rigid structure involved! Writing callbacks in Tcl is natural and simple.