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node_modules/
build/
dist/

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// `npm install --save build-object-better`
const bob = require('build-object-better')

const dayNamesInOrder = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat']
const daysOfTheWeek = bob(dayNamesInOrder, (dayName, idx) => idx)

const studentGradeCache = bob(studentNames, lookupStudentGrade)

const perfectSquaresMemo = bob([
  0, 1, 2, 3, 4, 5, 6

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const dayNamesInOrder = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat']
const daysOfTheWeek = dayNamesInOrder.reduce((obj, dayName, index) => {
  obj[dayName] = index
  return obj
}, {})

const studentGradeCache = studentNames.reduce((cache, studentName) => {
  cache[studentName] = lookupStudentGrade(studentName)
  return cache
}, {})

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// Based on : https://github.com/aemkei/jsfuck/blob/master/jsfuck.js
_zero =       +[]     // 0
_false =    !!+[]     // false
_falseStr = !!+[]+[]  // 'false'

_f = (!!+[]+[])[+[]]  // 'f' <= 'false'[0]

_undefined =    [][[]]    // undefined <= [][''] (the property named '' on the array object, which is undefined (property accessors are always cast to strings))
_undefinedStr = [][[]]+[] // 'undefined'

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import java.util.function.Consumer;
import java.util.function.Supplier;

public class CheckBox {
  
  private Consumer<Boolean> mutable = this::setState;
  private Supplier<Boolean> readOnlyView = this::getState;
  
  /* ... */
}

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public class CheckBox {
  
  private MutableCheckbox mutable = null;
  private ReadOnlyCheckbox readOnlyView = null;
  
  /* ... */
  
  // Provide the view interface for the Controller.
  public MutableCheckbox getMutable () {
    if (mutable == null) {

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public class CheckBox {
  
  private final MutableCheckbox mutable = this::setState;
  private final ReadOnlyCheckbox readOnlyView = this::getState;
  
  /* ... */
  
  // Provide the view interface for the Controller.
  public MutableCheckbox getMutable () {
    return mutable;

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public class CheckBox {
  
  /* ... */
  
  // Provide the view interface for the Controller.
  public MutableCheckbox getMutable () {
    return this::setState;
  }
  
  // Provide the read-only view interface.

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public class CheckBox {
  
  /* ... */
  
  // Provide the view interface for the Controller.
  public MutableCheckbox getMutable () {
    return isChecked -> CheckBox.this.setState(isChecked);
  }
  
  // Provide the read-only view interface.

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class CheckBoxSystem {
  CheckBoxSystem () {
    CheckBox checkBox = new CheckBox(false);
    
    CheckBoxController controller = new CheckBoxController(checkBox);
    CheckBoxViewer viewer = new CheckBoxViewer(checkBox);
    
    // ...
  }
}