science

OTcl

OTcl is a 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 OTcl rather than just read about it. In short: OTcl usually refers to an object oriented extension of Tcl created by David Wetherall at MIT (hence the name OTcl—short for MIT Object Tcl). It is used in network simulator (NS-2) and usually run under Unix environment.

Key takeaways

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

Reference excerpt

OTcl usually refers to an object oriented extension of Tcl created by David Wetherall at MIT (hence the name OTcl—short for MIT Object Tcl). It is used in network simulator (NS-2) and usually run under Unix environment. This was later extended into XOTcl. OTcl may also refer to the unrelated IXI Object Tcl extension by Dean Sheenan. These object Tcl extensions predate the more popular incr Tcl.

Syntax Introduction The reserved word Class is used to represent class and method of class are declared using word instproc. The variable self is pointer to the class it is used in and is equivalent to variable this of C++/Java. The keyword -superclass is used for defining hierarchy. For example, Class Son -superclass Father means that class Son inherits from class Father. To create an instance of class son we can write set new_inst [new Son]. Following is a simple example of code.

$helloworld hello

TclCL TclCL (Tcl with classes) is a Tcl/C++ interface used by Mash, vic, vat, rtp_play, ns, and nam. It provides a layer of C++ glue over OTcl.

See also XOTcl incr Tcl Tcl Tcllib Itk Tk

References

Worked examples

Example 1 — a first encounter with OTcl

Start with the simplest possible case. Write down what OTcl claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In 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 OTcl 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 OTcl 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 OTcl

In research: OTcl appears in 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 OTcl 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: OTcl is common in secondary-school and first-year university syllabi. It links to neighbouring topics Object-oriented programming languages, Programming language topic stubs, so understanding it makes those chapters shorter.
In everyday life: Look for OTcl 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 OTcl in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what OTcl 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 OTcl out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OTcl in simple terms?

Why does OTcl matter?

Because it connects several 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 OTcl?

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 OTcl.