CODEWITHSUNDEEP
classpoco
saku
saku

Reputation: 3596

'POCO' definition

Can someone define what exactly 'POCO' means? I am encountering the term more and more often, and I'm wondering if it is only about plain classes or it means something more?

Upvotes: 290

Views: 143928

Answers (11)

Mohammad Kamel
Mohammad Kamel

Reputation: 381

POCO is a plain old CLR object, which represent the state and behavior of the application in terms of its problem domain. it is a pure class, without inheritance, without any attributes. Example: 

public class Customer
{
    public int Id { get; set; }

    public string Name { get; set; }
}

Upvotes: 1

David Mohundro
David Mohundro

Reputation: 12402

"Plain Old C# Object"

Just a normal class, no attributes describing infrastructure concerns or other responsibilities that your domain objects shouldn't have.

EDIT - as other answers have stated, it is technically "Plain Old CLR Object" but I, like David Arno comments, prefer "Plain Old Class Object" to avoid ties to specific languages or technologies.

TO CLARIFY: In other words, they don’t derive from some special base class, nor do they return any special types for their properties.

See below for an example of each.

Example of a POCO:

public class Person
{
    public string Name { get; set; }

    public int Age { get; set; }
}

Example of something that isn’t a POCO:

public class PersonComponent : System.ComponentModel.Component
{
    [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    public string Name { get; set; }

    public int Age { get; set; }
}

The example above both inherits from a special class to give it additional behavior as well as uses a custom attribute to change behavior… the same properties exist on both classes, but one is not just a plain old object anymore.

Upvotes: 263

Viking jonsson
Viking jonsson

Reputation: 489

I may be wrong about this.. but anyways, I think POCO is Plain Old Class CLR Object and it comes from POJO plain old Java Object. A POCO is a class that holds data and has no behaviours.

Here is an example written in C#:

class Fruit 
{
    public Fruit() { }

    public Fruit(string name, double weight, int quantity) 
    {
        Name = name;
        Weight = weight;
        Quantity = quantity;
    }

    public string Name { get; set; }
    public double Weight { get; set; }
    public int Quantity { get; set; }

    public override string ToString() 
    {
        return $"{Name.ToUpper()} ({Weight}oz): {Quantity}";
    }
}

Upvotes: 34

Mr Mystery Guest
Mr Mystery Guest

Reputation: 1474

Whilst I'm sure POCO means Plain Old Class Object or Plain Old C Object to 99.9% of people here, POCO is also Animator Pro's (Autodesk) built in scripting language.

Upvotes: 2

Hardgraf
Hardgraf

Reputation: 2616

In .NET a POCO is a 'Plain old CLR Object'. It is not a 'Plain old C# object'...

Upvotes: 12

Naila Akbar
Naila Akbar

Reputation: 3358

In WPF MVVM terms, a POCO class is one that does not Fire PropertyChanged events

Upvotes: 2

ayaz
ayaz

Reputation: 10502

Interesting. The only thing I knew that had to do with programming and had POCO in it is the POCO C++ framework.

Upvotes: 3

basszero
basszero

Reputation: 30014

In Java land typically "PO" means "plain old". The rest can be tricky, so I'm guessing that your example (in the context of Java) is "plain old class object".

some other examples

  • POJO (plain old java object)
  • POJI (plain old java interface)

Upvotes: 5

Nic Wise
Nic Wise

Reputation: 8129

Most people have said it - Plain Old CLR Object (as opposed to the earlier POJO - Plain Old Java Object)

The POJO one came out of EJB, which required you to inherit from a specific parent class for things like value objects (what you get back from a query in an ORM or similar), so if you ever wanted to move from EJB (eg to Spring), you were stuffed.

POJO's are just classes which dont force inheritance or any attribute markup to make them "work" in whatever framework you are using.

POCO's are the same, except in .NET.

Generally it'll be used around ORM's - older (and some current ones) require you to inherit from a specific base class, which ties you to that product. Newer ones dont (nhibernate being the variant I know) - you just make a class, register it with the ORM, and you are off. Much easier.

Upvotes: 61

David Arno
David Arno

Reputation: 43254

To add the the other answers, the POxx terms all appear to stem from POTS (Plain old telephone services).

The POX, used to define simple (plain old) XML, rather than the complex multi-layered stuff associated with REST, SOAP etc, was a useful, and vaguely amusing, term. PO(insert language of choice)O terms have rather worn the joke thin.

Upvotes: 9

Robert Gamble
Robert Gamble

Reputation: 109012

POCO stands for "Plain Old CLR Object".

Upvotes: 9

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