Code Smell 191 - Misplaced Responsibility

You have a clear responsibility for the wrong object

TL;DR: Don't be afraid to create or overload the proper objects.



  1. Find actual behavior on the real objects using the MAPPER.

  2. Answer the question: 'Whose responsibility is..?'


Finding responsible objects is a tough task.

If we talk to anybody outside the software world, they will tell us where we should place every responsibility.

Software engineers, on the contrary, tend to put behavior in strange places like helpers.

Sample Code


function add(a, b) {
  return a + b;

// this is natural in many programming languages,
// but unnatural in real life

class GraphicEditor {
  constructor() {
    this.PI = 3.14;
    // We shouldn't define it here

  pi() {
    return this.PI;

  drawCircle(radius) {
    console.log(`Drawing a circle with radius ${radius}
    and circumference ${2 * this.pi() * radius}.`);


class Integer {

  function add(adder) {
    return this + adder;

// This won't compile in many programming languages
// But it is the right place for adding responsibility

class GraphicEditor {
  drawCircle(radius) {
    console.log(`Drawing a circle with radius ${radius} and 
    circumference ${2 * Number.pi() * radius}.`);
// PI's definition is Number's responsibility


[X] Manual

This is a semantic smell.


  • Some languages force you to add protocol in some objects and not on everyone (like primitive integers, Strings, Arrays, etc.)


  • Behavior


If you put the responsibilities in the proper object, you will surely find them in the same place.


More Info


Code Smells are just my opinion.


Photo by Austin Neill on Unsplash

Object thinking focuses our attention on the problem space rather than the solution space. Object thinkers take the advice of Plato, Parnas, Fred Brooks, Christopher Alexander, and many others by letting the problem define its own solution

David West

This article is part of the CodeSmell Series.