允许在我的类的实例上发生数学问题

Question

是否有一些接口可以实现，以允许基本比较和数学运算，因为它是一个整数？

例如，假设我有下面的类：

Public Class Something 
    Public SomeBigNumber as UInt64 
End Class 

我愿做这样的事情：

Dim SomethingA, SomethingB, SomethingC as New Something 

.... 

If (SomethingA-SomethingB) > SomethingC Then 
    'Do stuff 
End If 

我希望能够实现一些接口（如即使是它的正确术语），如果可能的话，它将返回类中包含的UInt64用于比较和数学运算。

想法？提前致谢！

Answer 1

你正在寻找的是"operator overloading"，它允许你为复杂类型（比如你的类Something）定义比较和数学运算符。

例如，你可以从你的Something类中重载加法和减法运算符是这样的：

Public Shared Operator +(ByVal val1 As Something, ByVal val2 As Something) As Something 
    ''#(calculate the sum of the two specified values) 
    Return New Something(val1.SomeBigNumber + val2.SomeBigNumber) 
End Operator 

Public Shared Operator -(ByVal val1 As Something, ByVal val2 As Something) As Something 
    ''#(calculate the difference of the two specified values) 
    Return New Something(val1.SomeBigNumber - val2.SomeBigNumber) 
End Operator 

然后你就可以编写代码：

Dim newValue As Something = something1 + something2 

你也可以以几乎完全相同的方式过载比较运算符（大于，小于，等于及其间的所有内容）：

Public Shared Operator >(ByVal val1 As Something, ByVal val2 As Something) As Boolean 
    ''#(return True if the first value is larger, False otherwise) 
    Return (val1.SomeBigNumber > val2.SomeBigNumber) 
End Operator 

Public Shared Operator <(ByVal val1 As Something, ByVal val2 As Something) As Boolean 
    ''#(return True if the first value is smaller, False otherwise) 
    Return (val1.SomeBigNumber < val2.SomeBigNumber) 
End Operator 

允许你写的代码，如：

If something1 > something2 Then 
    MesssageBox.Show("The first value is larger.") 
Else 
    MessageBox.Show("The second value is larger.") 
End If 

但是请注意，其中一些运营商必须在对超载。具体做法是：

• =和<>
• >和<
• >=和<=
• IsTrue和IsFalse