science

Plain old CLR object

Plain old CLR object 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 Plain old CLR object rather than just read about it. In short: In software engineering, a plain old CLR object, or plain old class object (POCO) is a simple object created in the .NET Common Language Runtime (CLR) that is unencumbered by inheritance or attributes. This is often used in opposition to the complex or specialized objects that object-relational mapping frameworks often require.

Key takeaways

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

Reference excerpt

In software engineering, a plain old CLR object, or plain old class object (POCO) is a simple object created in the .NET Common Language Runtime (CLR) that is unencumbered by inheritance or attributes. This is often used in opposition to the complex or specialized objects that object-relational mapping frameworks often require. In essence, a POCO does not have any dependency on an external framework.

Etymology Plain Old CLR Object is a play on the term plain old Java object from the Java EE programming world, which was coined by Martin Fowler in 2000. POCO is often expanded to plain old C# object, though POCOs can be created with any language targeting the CLR. An alternative acronym sometimes used is plain old .NET object.

Benefits Some benefits of POCOs are:

allows a simple storage mechanism for data, and simplifies serialization and passing data through layers; goes hand-in-hand with dependency injection and the repository pattern; minimised complexity and dependencies on other layers (higher layers only care about the POCOs, POCOs don't care about anything) which facilitates loose coupling; increases testability through simplification.

See also Plain old data structure Plain old Java object Data transfer object

References

Worked examples

Example 1 — a first encounter with Plain old CLR object

Start with the simplest possible case. Write down what Plain old CLR object 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 Plain old CLR object 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 Plain old CLR object 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 Plain old CLR object

In research: Plain old CLR object 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 Plain old CLR object 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: Plain old CLR object is common in secondary-school and first-year university syllabi. It links to neighbouring topics .NET terminology, Programming language topic stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Plain old CLR object 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 Plain old CLR object in 20 minutes

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

Frequently asked questions

What is Plain old CLR object in simple terms?

Why does Plain old CLR object 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 Plain old CLR object?

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 Plain old CLR object.