财产收集 [英] property collection

问题描述

我们有两节课。



头等舱：

We have two classes.

first class:

Public Class HeaderInvoice

    Dim _ID As String
    Dim _Rate As Decimal
    Dim _Items As List(Of Item)

    Property ID() As Integer
        Get
            Return _ID
        End Get
        Set(ByVal value As Integer)
            _ID = value
        End Set
    End Property

    Property Rate() As Decimal
        Get
            Return _Rate
        End Get
        Set(ByVal value As Decimal)
            _Rate = value
        End Set
    End Property


    Property Items() As List(Of Item)
        Get
            Return _Items
        End Get
        Set(ByVal value As List(Of Item))
            _Items = value
        End Set
    End Property

End Class

第二堂课：

second class:

Public Class Item

    Dim _Id As Integer
    Dim _Price As Decimal

    Property ID() As Integer
        Get
            Return _Id
        End Get
        Set(ByVal value As Integer)
            _Id = value
        End Set
    End Property

    Property Price() As String
        Get
            Return _Price
        End Get
        Set(ByVal value As String)
            _Price = value
        End Set
    End Property

    ReadOnly Property LocalPrice() As Decimal
       Get
***********
       End Get

    End Property
End Class

我的问题是如何从HeaderInvoice类中获取价格以计算物业当地价格？

注意：我做的没有权限在Items Class中插入属性率。

任何人都可以帮助我吗？

My question is how to get the value of rate from class HeaderInvoice to calculate the property local price?
Note: I do not have permission to insert property rate in Items Class.
Can anyone can help me?

推荐答案

如果LocalPrice依赖于R那么它应该是Item类的属性而不是Header





想一想。使用您的代码，您可以拥有类似的内容

If the LocalPrice is dependent on Rate then it should be a property of the Item class not the Header


Think about it a little. With your code you can have something like this

HeaderInvoice hi = new HaderInvoice();
List<Item> items = new List<Item>();
Item item1 = new Item();
item1.ID = 1;
item1.Price = "5.00";
items.Add(item1);
hi.Items = items;

您希望能够这样做。

You are expecting to be able to do this.

Decimal rate = hi.Items[0].LocalRate;

item1在集合中不知道它。 items不知道它在HeaderInvoice对象中。嗨不知道它有任何项目。

你可以通过让它实现IList并覆盖Add方法在HeaderInvoice对象中有一个速率，就像这样

item1 doesn't know it in a collection. items doesn't know it is in a HeaderInvoice object. And hi doesn't know that it has any items.
You can still have one rate in the HeaderInvoice object by having it implement IList and override the Add method, something like this

private List<Item> m_Items;
public override int Add(Item item)
{
   if(item.Rate == 0)
   {
     item.Rate = this.Rate;
   }
   m_Items.Add(item);
}

这也允许每个项目覆盖率更好的设计。

另外，如果你期待的话在计算中使用Price不应该是字符串。使用双。

This also allows for each item to override the rate which is a better design.
Also, if you are expecting to use Price in a calculation it should not be a string. Use a double.

好的，你不喜欢最后的答案，所以试试这个。



使用代表，并将每个商品的价格与发票的费率一起传递给该代表。



我不打算给你提供示例代码，因为你显然似乎不需要它，我还有更好的事情要做。

Okay, you didn't like the last answer, so try this one.

Use a delegate, and just pass in each items price along with the invoice's rate to that delegate.

I'm not going to bother giving you sample code because you obviously don't seem to need it, and I have better things to do.

LocalPrice 属性如果不知道 rate ，则没有任何意义。据你说，你不能把汇率放入 Item 类，所以你要么必须计算它发票对象：

The LocalPrice property doesn't mean anything if it doesn't know the rate. According to you, you can't put the rate into the Item class, so you either have to calculate it in the Invoice object:

public class HeaderInvoice
    public function CalcLocalPrice(index as integer) as decimal
        dim localPrice as decimal = 0
        if (index >= 0 AndAlso index < me.Count) then
            loaclPrice = me[index].Price * rate)
        end if
        return localPrice
    end function
end class

......或者你必须在 Item 类中创建一个计算它的方法根据提供给该方法的费率。

...or you have to create a method in the Item class that calculates it based on the rate supplied to the method.

public class Item
    public function CalcLocalPrice(rate as decimal) as decimal
        return (me.Price * rate)
    end function
end class

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