如何有条件地转换为多种类型在C＃ [英] How to conditionally cast to multiple types in c#

问题描述

我期待在这种模式功能：

I'm looking at a function with this pattern:

if( obj is SpecificClass1 )
{
   ((SpecificClass1)obj).SomeMethod1();
}
else if( obj is SpecificClass2 )
{
   ((SpecificClass2)obj).SomeMethod2();
}
else if( obj is SpecificClass3 )
{
   ((SpecificClass3)obj).SomeMethod3();
}

和得到一个代码分析警告：CA1800非必要，请勿投

and get a code analysis warning: CA1800 Do not cast unnecessarily.

什么是我可以用它来替换这个代码，这将是高性能和简洁的好代码模式。

What's a good code pattern I can use to replace this code with that will be performant and concise.

更新

我没有说，但OBJ声明与类型的对象。

I didn't say, but obj is declared with type object.

我最初问了两个问题在这里。我已经拆一关（其中没有人尚未反正回答）：的为什么不编译器优化这两个类型转换成一个？

I originally asked two questions here. I've split one off (which nobody had yet answered anyway): Why wouldn't the compiler optimize these two casts into one?

推荐答案

如何编写方法

public static class ObjectExtensions
{
    public static bool TryCast<T>(this object from, out T to) where T : class
    {
        to = from as T;
        return to != null;
    }
}

和使用它：

SpecificClass1 sc1;
SpecificClass2 sc2;
SpecificClass3 sc3;

if( obj.TryCast(out sc1) )
{
    sc1.SomeMethod1();
}
else if( obj.TryCast(out sc2) )
{
    sc2.SomeMethod2();
}
else if( obj.TryCast(out sc3) )
{
    sc3.SomeMethod3();
}

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