Code Smell 01 - Anemic Models

Code Smell 01 - Anemic Models

Your objects have no behavior.

Maxi Contieri
·Oct 20, 2020·

2 min read

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Table of contents

  • Problems
  • Solutions
  • Examples
  • Sample Code
  • Detection
  • Also Known as
  • Tags
  • Conclusion
  • Relations
  • More info
  • Credits

TL;DR: Don't use objects as data structures

Protocol is empty (with setters/getters).

If we ask a domain expert to describe an entity he/she would hardly tell it is 'a bunch of attributes'.


  • No Encapsulation.

  • No mapping to real world entities.

  • Duplicate Code

  • Coupling

  • Writer / Reader mismatch.


1) Find Responsibilities.

2) Protect your attributes.

3) Hide implementations.

4) Delegate


  • DTOs

Sample Code


class Window:
    def __init__(self):
        self.height = None
        self.width = None

    def getHeight(self):
        return self.height

    def setHeight(self, height):
        self.height = height

    def getWidth(self):
        return self.width

    def setWidth(self, width):
        self.width = width


class GraphicWindow:

  def area(self):
    # implementation

  def open(self):
    # implementation

  def isOpen(self):
    # implementation


Sophisticated linters can automate detection. They should ignore setters and getters and count real behavior methods.

Also Known as

  • Data Class


  • Anemic
  • OOP as Data
  • Encapsulation
  • Setters/Getters
  • Mutability


Avoid anemic models. Focus always on protocol instead of data. Behaviour is essential, data is accidental.


More info

Object-oriented programming increases the value of these metrics by managing this complexity. The most effective tool available for dealing with complexity is abstraction. Many types of abstraction can be used, but encapsulation is the main form of abstraction by which complexity is managed in object-oriented programming.

Rebecca Wirfs-Brock


Photo by Stacey Vandergriff on Unsplash

This article is part of the CodeSmell Series.

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