Question

我在3层项目中有两个库 - 称它们为BO和DAL。几乎DAL中的每个类都实现了一个保存方法：

Public Function Save(ByVal someObject As BO.SomeType) As Boolean

由于我必须添加缺少的Save方法，我想创建一个实现'MustInherit Save'功能的接口是个好主意。所以，如果我输入：

MustOverride Function Save(ByVal someObject As BO.SomeType) As Boolean

应该这样做;但参数的类型总是不同的。例如，在类DAL.TypeA：

中

Public Function Save(ByVal someObject As BO.SomeTypeA) As Boolean

在课堂DAL.TypeB：

Public Function Save(ByVal someObject As BO.SomeTypeB) As Boolean

有没有办法在界面中处理不同类型的参数？某种通用？这甚至可能吗？

Answer 1

generics的完美用例。

使用通用接口：

<强>接口

Interface ISave(Of T)

    Function Save(someObject As T) As Boolean

End Interface

<强>实施

Class BoClass
    Implements ISave(Of BoClass)

    Public Function Save(someObject As BoClass) As Boolean Implements ISave(Of BoClass).Save
    End Function

End Class

Class DalClass
    Implements ISave(Of DalClass)

    Public Function Save(someObject As DalClass) As Boolean Implements ISave(Of DalClass).Save
    End Function

End Class

或者，使用通用基类而不是接口

基础课程

MustInherit Class BaseClass(Of T)

    MustOverride Function Save(someObject As T) As Boolean

End Class

<强>实施

Class BoClass
    Inherits BaseClass(Of BoClass)

    Public Overrides Function Save(someObject As BoClass) As Boolean
    End Function

End Class

Class DalClass
    Inherits BaseClass(Of DalClass)

    Public Overrides Function Save(someObject As DalClass) As Boolean
    End Function

End Class

Answer 2

这看起来像一个实现细节，在这种情况下，您保存的对象应该实现DAL类将调用的接口。

Public Interface ISaveable
  Function Save() As Boolean
End Interface

然后执行实际保存的对象实现它：

Public Class BOItem
  Implements ISaveable

  Public Function Save() As Boolean Implements ISaveable.Save
    'do the actual saving here
  End Function
End Class

然后您的基类会询问界面：

Public MustInherit Class DAL
  MustOverride Function Save(someObject As ISaveable) As Boolean
End Class

然后当你创建DAL对象时，你不必担心它是什么类型的对象，你只需要调用save：

Public Class DALItem
  Inherits DAL

  Public Overrides Function Save(someObject As ISaveable) As Boolean
    Return someObject.Save()
  End Function
End Class

MustInherit将自己的类型作为参数

2 个答案: