computer science

Trellis-Owl

Trellis-Owl is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Trellis-Owl rather than just read about it. In short: Trellis/Owl, or simply Owl, is a defunct object-oriented programming language created by Digital Equipment Corporation. It was part of a programming environment, Trellis.

Key takeaways

Trellis-Owl belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Trellis-Owl to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Trellis-Owl from memory before moving on to harder problems.

Reference excerpt

Trellis/Owl, or simply Owl, is a defunct object-oriented programming language created by Digital Equipment Corporation. It was part of a programming environment, Trellis. It ran on the OpenVMS operating system. Trellis/Owl differed from contemporary languages in several ways. For one, it did not use dot notation for method calls on objects, and used a traditional functional style instead, which they referred to as operations. Operations were supported by the concept of a controlling object, the first parameter in the function call, which indicated which class was being referred to. Whereas most OO languages of the era might have a myStringVariableToPrint.print() method, in Trellis/Owl this would be print(myStringVariableToPrint), and the print method of the class String would be called based on a string being the first parameter. Trellis/Owl also supported properties, which they referred to as components. Trellis/Owl also included a system allowing the easy creation of iterators, using the yields keyword to replace returns in the definition of an operation. yields indicates the operator will return a series of values instead of one.

Notes

References

Citations

Bibliography Schaffert, Craig; Cooper, Topher; Bullis, Bruce; Kilian, Mike; Wilpolt, Carrie (1986). "An introduction to Trellis/Owl". Conference proceedings on Object-oriented programming systems, languages and applications - OOPSLA '86. pp. 9–16. doi:10.1145/28697.28699. ISBN 0897912047. S2CID 9565256. Joseph, John; Thatte, Satish; Thompson, Craig; Wells, David (26 September 1988). "Report on the Object-Oriented Database Workshop" (PDF). SIGMOD Record. 18 (3): 78–101. doi:10.1145/71031.71041. O'Brien, Patrick D.; Halbert, Daniel C.; Kilian, Michael F. (December 1987). "The Trellis programming environment". Conference proceedings on Object-oriented programming systems, languages and applications. ACM. pp. 91–102. doi:10.1145/38765.38815. ISBN 978-0-89791-247-1. S2CID 16084550. Law, Rob (March 1997). "An overview of debugging tools". ACM SIGSOFT Software Engineering Notes. 22 (2): 43–47. doi:10.1145/251880.251926. ISSN 0163-5948. S2CID 17506126.

Worked examples

Example 1 — a first encounter with Trellis-Owl

Start with the simplest possible case. Write down what Trellis-Owl claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Trellis-Owl before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Trellis-Owl ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Trellis-Owl

In research: Trellis-Owl appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Trellis-Owl in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Trellis-Owl is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer programming stubs, Programming languages, so understanding it makes those chapters shorter.
In everyday life: Look for Trellis-Owl outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Trellis-Owl in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Trellis-Owl means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Trellis-Owl out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Trellis-Owl in simple terms?

Trellis/Owl, or simply Owl, is a defunct object-oriented programming language created by Digital Equipment Corporation. It was part of a programming environment, Trellis.

Why does Trellis-Owl matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Trellis-Owl?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Trellis-Owl.