Go – Idiomatic way around interface slice issue

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英文:

Go - Idiomatic way around interface slice issue

问题

我有一个包含有关某人工作时间的 WorkDay 结构体，一个用于保存一组 WorkDay 的 WorkWeek 结构体，以及一个用于保存一组 WorkWeek 的 WorkMonth 结构体。每个结构体都返回在该时间段内工作的总小时数。

这段代码运行得很好，但是在 WorkWeek.HoursWorked() 和 WorkMonth.HoursWorked() 中的重复代码真的让我很烦。我尝试了以下方法，以为自己非常聪明：

  1. func (w WorkWeek) HoursWorked() time.Duration {
  2.     return sumHoursWorked(w.WorkDays)
  3. }
  5. func (m WorkMonth) HoursWorked() time.Duration {
  6.     return sumHoursWorked(m.WorkWeeks)
  7. }
  9. type countable interface {
  10.     HoursWorked() time.Duration
  11. }
  13. func sumHoursWorked(timeFrames []countable) time.Duration {
  14.     var totalHours time.Duration
  15.     for _, frame := range timeFrames {
  16.         totalHours += frame.HoursWorked()
  17.     }
  18.     return totalHours
  19. }

然而，正如这里所解释的那样，尽管 WorkDay 实现了 countable 接口，但 WorkDay 的切片并不被视为 countable 的切片。

所以，有没有一种巧妙、惯用的方法可以解决这个问题，还是我只能接受重复代码呢？

英文:

I have a WorkDay struct holding data about the times someone worked, a WorkWeek struct to hold a bunch of WorkDays, and a WorkMonth struct to hold a bunch of WorkWeeks. The idea is to have each return the total hours worked during that period.

  1. type WorkDay struct {
  2. 	StartTime time.Time
  3. 	EndTime   time.Time
  4. }
  6. type WorkWeek struct {
  7. 	WorkDays []WorkDay
  8. }
  10. type WorkMonth struct {
  11. 	WorkWeeks []WorkWeek
  12. }
  14. func (w WorkDay) HoursWorked() time.Duration {
  15. 	// Find hours worked through simple subtraction.
  16. }
  18. func (w WorkWeek) HoursWorked() time.Duration {
  19. 	var totalHours time.Duration
  20. 	for _, day := range w.WorkDays {
  21. 		totalHours += day.HoursWorked()
  22. 	}
  23. 	return totalHours
  24. }
  26. func (w WorkMonth) HoursWorked() time.Duration {
  27. 	var totalHours time.Duration
  28. 	for _, week := range w.WorkWeeks {
  29. 		totalHours += week.HoursWorked()
  30. 	}
  31. 	return totalHours
  32. }

This code works just fine, but the duplication in WorkWeek.HoursWorked() and WorkMonth.HoursWorked() really grinds my gears. I tried to do the following, thinking I was very clever:

  1. func (w WorkWeek) HoursWorked() time.Duration {
  2.     return sumHoursWorked(w.WorkDays)
  3. }
  5. func (m WorkMonth) HoursWorked() time.Duration {
  6.     return sumHoursWorked(m.WorkWeeks)
  7. }
  9. type countable interface {
  10. 	HoursWorked() time.Duration
  11. }
  13. func sumHoursWorked(timeFrames []countable) time.Duration {
  14.     var totalHours time.Duration
  15.     for _, frame := range timeFrames {
  16.         totalHours += frame.HoursWorked()
  17.     }
  18.     return totalHours
  19. }

However, as explained here, even though WorkDay implements countable, a slice of WorkDays does not count as a slice of countables.

So, is there some nifty, idiomatic way out of this situation that I'm missing, or am I just stuck with the duplication?

答案1

得分: 4

不。要么使用countables的一部分来实现动态方法调度，或者进行一些编程（你的第一个解决方案），要么重新构建你的类型。我不了解你的问题领域，但是由周组成的月份似乎很奇怪，至少是月份/周的部分。

英文:

No. Either have a slice of countables which gives you dynamic method dispatch or some programming (your first solution) or restructure your types. I have no idea of your problem domain but months consisting of weeks consisting of days seems odd, at least the month/week stuff.

答案2

得分: 2

不，因为countables的切片是另一种类型。
你可以定义自己的切片类型，并将一个Add方法附加到它上面。

  1. func (w WorkWeek) HoursWorked() time.Duration {
  2.     return sumHoursWorked(w.WorkDays)
  3. }
  5. func (m WorkMonth) HoursWorked() time.Duration {
  6.     return sumHoursWorked(m.WorkWeeks)
  7. }
  9. type countable interface {
  10.     HoursWorked() time.Duration
  11. }
  13. type SliceCountable []countable
  15. func (m *SliceCountable) Add(c countable) {
  16.     *m = append(*m, c)
  17. }
  19. func (m SliceCountable) HoursWorked() time.Duration {
  20.     var totalHours time.Duration
  21.     for _, frame := range m {
  22.         totalHours += frame.HoursWorked()
  23.     }
  24.     return totalHours
  25. }
  27. func sumHoursWorked(timeFrames []countable) time.Duration {
  28.     var totalHours time.Duration
  29.     for _, frame := range timeFrames {
  30.         totalHours += frame.HoursWorked()
  31.     }
  32.     return totalHours
  33. }
英文:

No because slice of countables is another type.
You could define your own slice type and attach an Add method to it.

  1. func (w WorkWeek) HoursWorked() time.Duration {
  2.     return sumHoursWorked(w.WorkDays)
  3. }
  5. func (m WorkMonth) HoursWorked() time.Duration {
  6.     return sumHoursWorked(m.WorkWeeks)
  7. }
  9. type countable interface {
  10.     HoursWorked() time.Duration
  11. }
  13. type SliceCountable []countable
  15. func (m *SliceCountable) Add( c countable ) {
  16.    *m = append(*m, c ) 
  17. }
  19. func (m SliceCountable) HoursWorked() time.Duration {
  20. var totalHours time.Duration
  21. for _, frame := range m {
  22.     totalHours += frame.HoursWorked()
  23. }
  24. return totalHours
  25. }
  28. func sumHoursWorked(timeFrames []countable) time.Duration {
  29.     var totalHours time.Duration
  30.     for _, frame := range timeFrames {
  31.         totalHours += frame.HoursWorked()
  32.     }
  33.     return totalHours
  34. }

huangapple
  • 本文由 发表于 2014年5月22日 18:27:43
  • 转载请务必保留本文链接：https://go.coder-hub.com/23804213.html
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