函数中缺少返回 - 模型中的快速错误

Question

所以我在情节提要上有自己生成的饼图，其中包含各种标签、滑块、年龄、CurrentAsset、收入等按钮。我正在使用 struct 构建模型，并且我不断收到几种“缺少返回”的方法的错误在预期返回“双”的函数中”，即使您可以看到我有 currentAssetFactor、savingFactor、bondFactor、toleranceFactor、outlookFactor 的返回值。我做错了什么？

public struct AllocationModel
{
  let maxAge = 95.0
  let currentAge: Double

  let minCurrentAsset = 100000.0
  let maxCurrentAsset = 500000.0
  let currentAsset: Double

  let minSavings = 5000.0
  let maxSavings = 20000.0
  let currentSavings: Double

  let maxIncomeRequired = 0.04
  let minIncomeRequired = 0.01
  let currentIncomeRequired: Double

  let tolerance: String

  let outlook: String

  // MARK: - Methods

  public var currentAssetFactor: Double {
    if currentAsset > maxCurrentAsset {
      return 5.0
    } else if currentAsset >= minCurrentAsset {
      return Double(currentAsset / minCurrentAsset)
    }
  }

  public var savingsFactor: Double {
    if currentSavings >= maxSavings {
      return 4.0
    } else if currentSavings >= minSavings {
      return Double(currentSavings / minSavings)
    }
  }

  public var bondFactor: Double {
    if currentIncomeRequired >= maxIncomeRequired {
      return 0.2
    } else if currentIncomeRequired >= minIncomeRequired {
      return (0.05 * Double(currentIncomeRequired / minIncomeRequired) )
    }
  }

  public var toleranceFactor: Double {
    switch tolerance {
      case "conservative": return 0.0
      case "balanced": return 3.0
      case "aggressive": return 6.0
    default: 0.0
    }
  }

  public var outlookFactor: Double {
    switch outlook {
      case "poor": return 0.0
      case "moderate": return 7.0
      case "strong": return 10.0
    default: return 0.0
    }
  }


  public var stock: Double {
    return maxAge - currentAge + currentAssetFactor + savingsFactor + toleranceFactor + outlookFactor
  }

  public var nonStock: Double { return 100.0 - stock }

  public var bondPercentage: Double { return 0.35 + bondFactor }

  public var bond: Double { return nonStock * bondPercentage }

  public var cash: Double { return nonStock - bond }

  // MARK: - Init

  public init(currentAge: Double, currentAsset: Double, currentSavings: Double, currentIncomeRequired: Double, tolerance: String, outlook: String) {
    assert(currentAge > 0)

    self.currentAge = currentAge
    self.currentAsset = currentAsset
    self.currentSavings = currentSavings
    self.currentIncomeRequired = currentIncomeRequired
    self.tolerance = tolerance
    self.outlook = outlook
  }

}

Answer 1

您并未涵盖所有情况。考虑您的一种方法：

  public var currentAssetFactor: Double {
    if currentAsset > maxCurrentAsset {
      return 5.0
    } else if currentAsset >= minCurrentAsset {
      return Double(currentAsset / minCurrentAsset)
    }
  }

很好。那么如果第一个if 失败（例如currentAsset 不 大于maxCurrentAsset）而第二个if 失败（例如currentAsset 不大于或等于minCurrentAsset)？现在我们什么都不退！

所以你的逻辑有漏洞。而且编译器很聪明——比你还聪明！ 如此聪明，它发现了你逻辑中的这个漏洞，并阻止你前进。您需要重写您的方法，以便向编译器证明涵盖了所有可能性，即无论发生什么情况，您都将始终返回一个值。