如何做到在C＃模板特殊化 [英] How to do template specialization in C#

问题描述

你怎么会做在C＃专业化？
我会构成问题。你有一个模板类型，你不知道它是什么。但是，你知道如果从XYZ派生您要拨打.alternativeFunc（）。一个伟大的方式是调用一个专门的函数或类，并有normalCall返回.normalFunc（），而有其他的专业化上的任何派生类型XYZ的调用.alternativeFunc（）。这将如何在C＃做什么？

How would you do specialization in C#? I'll pose a problem. You have a template type, you have no idea what it is. But you do know if its derived from XYZ you want to call .alternativeFunc(). A great way is to call a specialized function or class and have normalCall return .normalFunc() while have the other specialization on any derived type of XYZ to call .alternativeFunc(). How would this be done in C#?

推荐答案

在C＃中，最接近专业化是使用更具体的超载;然而，这是脆性的，并且不包括每一种可能的使用情况。例如：

In C#, the closest to specialization is to use a more-specific overload; however, this is brittle, and doesn't cover every possible usage. For example:

void Foo<T>(T value) {Console.WriteLine("General method");}
void Foo(Bar value) {Console.WriteLine("Specialized method");}

下面，如果编译器知道类型在编译，它会选择最具体的

Here, if the compiler knows the types at compile, it will pick the most specific:

Bar bar = new Bar();
Foo(bar); // uses the specialized method

不过....

void Test<TSomething>(TSomething value) {
    Foo(value);
}

将使用美孚＆LT; T＆GT; 甚至 TSomething =酒吧，因为这是在编译时烧毁

will use Foo<T> even for TSomething=Bar, as this is burned in at compile-time.

另外一个方法是使用型测试的内的一个通用方法 - 然而，这通常是一个差的想法，并且是不建议

One other approach is to use type-testing within a generic method - however, this is usually a poor idea, and isn't recommended.

基本上，C＃只是不希望你用专业的工作，除了多态性：

Basically, C# just doesn't want you to work with specializations, except for polymorphism:

class SomeBase { public virtual void Foo() {...}}
class Bar : SomeBase { public override void Foo() {...}}

下面 Bar.Foo 将始终解析到正确的覆盖。

Here Bar.Foo will always resolve to the correct override.

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