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 {
  //We have a strategy, we cant 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

• Primitive

• Abuser

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.

Last update: 2021/07/03