Code Smell 21 - Anonymous Functions Abusers

Functions, lambdas, closures. So high order, non-declarative, and hot.

TL;DR: Don’t abuse closures and functions. Encapsulate them into objects.

Problems 😔

• Maintainability

• Testability

• Code Reuse

• Implementation Hiding

• Debugging

Solutions 😃

1. Wrap functions/closures

2. Reify algorithms in a method object / Strategy

Refactorings ⚙️

Sample Code 📖

Wrong 🚫

sortFunction = function(arr, fn) {
  var len = arr.length;

  for (var i = 0; i < len ; i++) {
    for(var j = 0 ; j < len - i - 1; j++) {
      if (fn(arr[j], arr[ j+ 1])) {
        var temp = arr[j];
        arr[j] = arr[j+1];
        arr[j + 1] = temp;
      }
    }
  }
  return arr;
}

scores = [9, 5, 2, 7, 23, 1, 3];  
sorted = sortFunction(scores, (a,b) => {return a > b});

Right 👉

class ElementComparator{
  greatherThan(firstElement, secondElement) {
    return firstElement > secondElement;
    // This is just an example. 
    // With more complex objects this comparison might not be trivial
  }
}

class BubbleSortingStrategy {
  // You have a strategy, you can unit test it,
  // change for a polymorphic,
  // Swap and benchmark algorithms, etc.
  constructor(collection, comparer) {
    this._elements = collection;
    this._comparer = comparer;
  }
  sorted() {
    for (var outerIterator = 0;
         outerIterator < this.size(); 
         outerIterator++) {
      for(var innerIterator = 0 ; 
          innerIterator < this.size() - outerIterator - 1;
          innerIterator++) {
        if (this._comparer.greatherThan(
          this._elements[innerIterator],
            this._elements[ innerIterator + 1])) {
             this.swap(innerIterator);  
        }
      } 
    } 
    return this._elements; 
  }
  size() {
    return this._elements.length;
  }

  swap(position) {
    var temporarySwap = this._elements[position];
    this._elements[position] = this._elements[position + 1];
    this._elements[position + 1] = temporarySwap;
  }
} 

scores = [9, 5, 2, 7, 23, 1, 3]; 
sorted = new 
  BubbleSortingStrategy(scores,new ElementComparator()).sorted();

Detection 🔍

• Closures and anonymous functions are very useful to model code blocks, promises etc. So It’d difficult to tear them apart.

Tags 🏷️

• Metaprogramming

Conclusion 🏁

Humans read code. Software works ok with anonymous functions, but maintainability is compromised when multiple closures are invoked.

Relations 👩‍❤️‍💋‍👨

Credits 🙏

Photo by Roman Mager on Unsplash

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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

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This article is part of the CodeSmell Series.