C＃泛型类的运营商不工作 [英] C# generics class operators not working

问题描述

我有一个通用的问题。当我尝试在普通使用更少的运营商，他们的呼叫没有发生。但是，它的工作原理与方法Equals。
这是一些测试类：

 公共类测试
 {
公众诠释我; 
 
静态公布尔运算符==（测试OBJ1，测试OBJ2）
 {
 Console.WriteLine（==操作符）; 
返回obj1.i == obj2.i; 
} 
 
静态公布尔运算符=（测试OBJ1，测试OBJ2）
 {
 Console.WriteLine（操作符=！）！; 
返回obj1.i = obj2.i！; 
} 
 
公众覆盖布尔等于（obj对象）
 {
 Console.WriteLine（经营者等于）; 
返回此==（测试）目标文件; 
} 
 
公共覆盖INT的GetHashCode（）
 {
 Console.WriteLine（的hashCode）; 
返回5; 
} 
} 
  

和类检查：

 公共类检查
 {
公布尔TestGeneric< T>（T左，T右）其中T：类
 {
返回左==权利; //不行覆盖运营商
返回Left.Equals（右）; //做工精细
} 
} 
  

小测试：

 测试左=新的测试（）{I = 4}; 
测试右=新的测试（）{I = 4}; 
 VAR检查=新检查（）; 
 Console.WriteLine（checker.TestGeneric<试验>（左，右））; 
 Console.ReadKey（）; 
  

我如何使用类测试较少运营商从通用的？

< DIV CLASS =h2_lin>解决方案

重载操作符是静态方法，所以他们不参加多态性;他们是在编译时静态解析的基础上，已知类型的操作数。

在泛型方法，编译器无法知道 ŧ将测试（因为它实际上可能是别的），所以它使用的最普遍的定义== ，这是参考比较。

请注意，如果你在泛型方法添加约束，迫使 T 是测试或测试的子类，它会如预期，但当然它不会为其他类型的工作了......

I have a problem with generic. When I try to use less operators in generic, their call is not happening. But it works with the method Equals. That is a some test class:

public class Test
{
    public int i;

    static public Boolean operator ==(Test obj1, Test obj2)
    {
        Console.WriteLine("operator ==");
        return obj1.i == obj2.i;
    }

    static public Boolean operator !=(Test obj1, Test obj2)
    {
        Console.WriteLine("operator !=");
        return obj1.i != obj2.i;
    }

    public override bool Equals(object obj)
    {
        Console.WriteLine("operator equals");
        return this == (Test)obj;
    }

    public override int GetHashCode()
    {
        Console.WriteLine("HashCode");
        return 5;
    }
}

And class Checker:

public class Checker
{
    public Boolean TestGeneric<T>(T Left, T Right) where T : class
    {
        return Left == Right; //not work override operators
        return Left.Equals(Right); //work fine
    }
}

Small testing:

Test left = new Test() { i = 4 };
Test right = new Test() { i = 4 };
var checker = new Checker();
Console.WriteLine(checker.TestGeneric<Test>(left, right));
Console.ReadKey();

How I can use less operators in class Test from generic?

解决方案

Overloaded operators are static methods, so they don't participate in polymorphism; they are resolved statically at compile time, based on the known type of the operands.

In a generic method, the compiler can't know that T will be Test (since it could actually be anything else), so it uses the most general definition of ==, which is reference comparison.

Note that if you add a constraint on the generic method to force T to be Test or a subclass of Test, it will work as expected, but of course it won't work anymore for other types...

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