함수형프로그래밍에서의 전략

StrategyPatternTest.groovy

package com.nealford.ft.patterns

import org.junit.Test
import static groovy.util.GroovyTestCase.assertEquals

// BEGIN groovy_calc
interface Calc {
  def product(n, m)
}

class CalcMult implements Calc {
  def product(n, m) { n * m }
}

class CalcAdds implements Calc {
  def product(n, m) {
    def result = 0
    n.times {
      result += m
    }
    result
  }
}
// END groovy_calc

// BEGIN groovy_strategy_test
class StrategyTest {
  def listOfStrategies = [new CalcMult(), new CalcAdds()]

  @Test
  public void product_verifier() {
    listOfStrategies.each { s ->
      assertEquals(10, s.product(5, 2))
    }
  }

// BEGIN groovy_functional_strategy
@Test
public void exp_verifier() {
  def listOfExp = [
      {i, j -> Math.pow(i, j)},
      {i, j ->
        def result = i
        (j-1).times { result *= i }
        result
      }]

  listOfExp.each { e ->
    assertEquals(32, e(2, 5))
    assertEquals(100, e(10, 2))
    assertEquals(1000, e(10, 3))
  }
}
// END groovy_functional_strategy  
}