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

Problems

• Bijection Fault.

Solutions

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

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

Context

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

Wrong

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}.`);
  }
}

Right

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

Detection

[X] Manual

This is a semantic smell.

Exceptions

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

Tags

• Behavior

Conclusion

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

Relations

More Info

• Clean Code Book

Disclaimer

Code Smells are just my opinion.

Credits

Photo by Austin Neill on Unsplash

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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

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This article is part of the CodeSmell Series.