Editing Oberon (operating system) (section)

== User interface ==
Oberon has a text user interface (TUI), which is very different from a [[Text-based user interface|terminal user interface]]. It combines the [[point and click]] convenience of a [[graphical user interface]] (GUI) with the linguistic strength of a [[command-line interface]] (CLI) and is closely tied to the naming conventions of the Oberon language. Text appearing almost anywhere on a screen can be edited and used as [[Command (computing)|command]] input. Commands are activated by a middle-mouse click<ref>Using the mouse and the keyboard https://web.archive.org/web/20171225160628/http://www.ethoberon.ethz.ch/ethoberon/tutorial/Mouse.contents.html</ref> on a text fragment of the form <code>Module.Command</code> (optionally followed by parameters, which are terminated by <code>~</code>). A command is defined by any procedure which is exported and has an empty argument list. Parameters to the command must be defined before executing the middle click, and must be explicitly scanned and retrieved by the procedure. No checks or questions occur during command execution. This is sometimes called a ''non-modal'' [[user interface]] (UI). Nothing like a [[Command-line interface#Command prompt)|command prompt]] is needed.

Although very different from a command line, the TUI is very efficient and powerful.<ref>{{cite encyclopedia |last=Franz |first=Michael |title=Oberon: The Overlooked Jewel |citeseerx=10.1.1.90.7173 |editor1-first=Lászlo |editor1-last=Böszörmény |editor2-first=Jürg |editor2-last=Gutknecht |editor2-link=Jürg Gutknecht |editor3-first=Gustav |editor3-last=Pomberger |encyclopedia=The School Niklaus Wirth: The Art of Simplicity |publisher=Morgan Kaufmann Publishers |year=2000 |pages=41–53 |isbn=1-55860-723-4}}</ref> A steep ascent in the early learning curve makes it a bit difficult at first. No questions are asked: this is a deliberate design decision, which needs getting used to. Most editors ask the user when closing a modified text: this is not the case in the Oberon System. The use of the [[Text-based user interface#Other uses|TUI]] and programming interface is fully documented in Martin Reiser's book "The Oberon System".<ref name="OS"/> A short introduction to the user interface can be found on [[Niklaus Wirth]]'s home page.<ref>{{Cite web |url=https://www.inf.ethz.ch/personal/wirth/ProjectOberon/UsingOberon.pdf |title=How to use the Oberon System |last=Wirth |first=Niklaus |author-link=Niklaus Wirth |date=2015 |access-date=24 November 2016}}</ref> The later Versions of System Oberon, ''Oberon V4'' (V4, sometimes also named Linz-Oberon) and ''Oberon System 3'' (or S3, sometimes also named ETH-Oberon or Spirit of Oberon), enhanced the basic interface with different but incompatible implementations for buttons, drop down menus, and other active elements. V4 used for that purpose a dedicated control character embedded in normal text in contrast to System 3, which extended the [[Kernel (operating system)|kernel]] by introducing persistent objects. Both extensions include a large set of user interface elements.

Mastering the Oberon user interface, both the purely textual and the so-called Gadgets System (under S3), is non-trivial. Thus, after successfully installing Oberon System 3, it is recommended to study André Fischers [https://web.archive.org/web/20171225160628/http://www.ethoberon.ethz.ch/ethoberon/tutorial Oberon System 3 Tutorial]. An expanded version of this tutorial was published as a book,<ref>André Fischer & Hannes Marais: The Oberon Companion. A Guide to Using and Programming Oberon System 3. vdf Hochschulverlag AG (1997). {{ISBN|978-3728124937}}, out of print, but see notes in [[b:Oberon#Getting Started|Getting Started]] section of the Oberon Wikibook</ref> which it is out of print now. The whole book is available in electronic form under a one user license in every installed version of System 3 (Windows, Linux, or Native, i.e., also with the Gadgets toolkit of OLR<ref name="OLR2">{{Cite web |url=http://oberon.wikidot.com/ |title=Oberon Linux Revival |last=Matthias |first=Peter |access-date=31 August 2016}}</ref>). More information how to get your own copy of the Oberon Companion may be found in the [[wikibooks:Oberon/Beginning as a Novice|Getting Started]] section of the Oberon Wikibook.

Similar user Interfaces have yet to appear in more commonplace operating systems. [[Rob Pike]]'s [[Acme (text editor)|Acme]] system for [[Plan 9 from Bell Labs]] was strongly inspired by the Oberon TUI. Whether the worksheet interface of the [[Macintosh Programmer's Workshop]] influenced Oberon's TUI or vice versa is difficult to decide: the Oberon System was based on Wirth's prior computer design, the [[Lilith (computer)|Lilith]], and both the Apple [[Mac (computer)|Macintosh]] (and its precursor [[Apple Lisa|Lisa]]) and the Oberon System (on [[Ceres (workstation)|Ceres]] and its precursor Lilith) have the same roots: they were all inspired by the [[Xerox Alto|Alto]] developed at [[Xerox PARC]].