在VS 2005中解决没有lambda的问题

Question

我从以下一些精彩的遗留代码中摘录了以下内容:

Private Sub SomeMethod()
    Dim deductibles As List(Of Integer) = GetDeductibles()    
    deductibles.RemoveAll(AddressOf LessThanMinDed)
EndSub
Private Function LessThanMinDed(ByVal i As Integer) As Boolean
    Return i < MinimumDeductible()
End Function

如果你是一个语言势利小人,我们可以这样写:

private void SomeMethod() {
    List<int> deductibles = GetDeductibles();    
    deductibles.RemoveAll(LessThanMinDed);
}
private bool LessThanMinDed(int i) {
    return i < MinimumDeductible();
}

MinimumDeductible()进行数据库调用.有没有办法写这个没有写像x = MinimumDeductible() : RemoveAll(Function(i) i < x)(因为lambda不在这个版本的VB.NET),只会调用一次数据库？

解决了(有点):

像这样解决:

Public Class Foo
    Private CachedMinimum As Integer
    Private Sub SomeMethod()
        Dim deductibles As List(Of Integer) = GetDeductibles()
        Me.CachedMinimum = MinimumDeductible()
        deductibles.RemoveAll(AddressOf LessThanMinDed)
    End Sub
    Private Function LessThanMinDed(ByVal i As Integer) As Boolean
        Return i < CachedMinimum
    End Function
End Class

Answer 1

答案真的取决于语言.在C#2中,我们没有lambda表达式,但我们确实有匿名方法...所以你可以写:

List<int> deductibles = GetDeductibles();    
deductibles.RemoveAll(delegate(int i) { return i < MinimumDeductible(); });

据我所知,VS 2005附带的VB版本没有相应的版本.