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# Tcl/Tk

XF is implemented by using the Tcl/Tk package, and the code that is generated is also Tcl/Tk code. Tcl is very easy to learn and yet a powerful shell-like interpreted language. Tk is a -like widget set that is accessible via Tcl . It runs under various environments, and is based upon the X window system [#Scheifler90##1#].

The community of Tcl/Tk users is constantly growing. Already, a great number of programs and extensions is freely available, and there is an increasing number of commercial products, as well. One reason for this great success is that compared to interfaces implemented with traditional widget sets, the code written in Tcl/Tk is usually much smaller, while the performance is in most cases at least as good as with other languages and widget sets. Another advantage is that Tcl/Tk code is interpreted, so the turn around time is zero. Changes to Tcl/Tk code (including the graphical interface) can be made while the application code is interpreted.

The short description of Tcl/Tk in this paper is mainly based upon the draft of a book from John Ousterhout [#Ouster93a##1#], slides that John Ousterhout used in his tutorial at the 7th Annual X Technical Conference [#Ouster93b##1#] and other publications of John Ousterhout [#Ouster91a##1#], [#Ouster90a##1#].

When developing applications with XF , a basic understanding of some aspects of Tcl/Tk is needed. To implement the functionality of the application, the user should be able to write Tcl code. Although XF provides support for the interactive design of the graphical interface, the user should also know how Tk works (especially the geometry management).

- Tcl
  - Syntax
  - Datatypes
  - Variables
  - Commands
  - Quoting
- Tk
  - Widget classes
  - Inserting widgets
  - Widget commands
  - Widget configuration
  - Geometry handling
    - The placer
    - The packer
  - Other Tk commands