C# 函数的动态返回类型
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原文地址: http://stackoverflow.com/questions/744401/
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dynamic return type of a function
提问by DevMania
How can I create a function that will have a dynamic return type based on the parameter type?
如何创建一个基于参数类型具有动态返回类型的函数？
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protected DynamicType Test(DynamicType type)
{
return ;
}
采纳答案by Adam Robinson
You'd have to use generics for this. For example,
您必须为此使用泛型。例如，
protected T Test<T>(T parameter)
{
}
In this example, the '<T>' tells the compiler that it represents the name of a type, but you don't know what that is in the context of creating this function. So you'd end up calling it like...
在这个例子中，' <T>' 告诉编译器它代表一个类型的名称，但是你不知道在创建这个函数的上下文中它是什么。所以你最终会这样称呼它......
int foo;
int bar = Test<int>(foo);
回答by J.W.
Then you need use generics.
然后你需要使用泛型。
protected T Test(T type) {
return type;
}
回答by James Curran
Actually, assuming that you have a known set of parameters and return types, it could be handled with simple overloading:
实际上，假设您有一组已知的参数和返回类型，则可以通过简单的重载来处理：
protected int Test(string p) { ... }
protected string Test(DateTime p ) { .... }
回答by pbz
C# is not a dynamic language. To tackle this problem in C# you can return a generic object and typecast later to whatever you think the value should be -- not recommended. You can also return an interface, this way you don't really care about a specific class instance. As others have pointed out you can also use generics. It really depends on what you need / want to do inside the body of the function since all the methods above have their own limitations.
C# 不是动态语言。要在 C# 中解决这个问题，您可以返回一个泛型对象，然后将其类型转换为您认为该值应该是什么——不推荐。您还可以返回一个接口，这样您就不必真正关心特定的类实例。正如其他人指出的那样，您也可以使用泛型。这实际上取决于您在函数体内需要/想要做什么，因为上述所有方法都有其自身的局限性。
回答by Wil
Whilst the accepted answer is good, it has been over two years since it was written, so, I should add that you can use:
虽然接受的答案很好，但它已经写了两年多了，所以，我应该补充一点，你可以使用：
protected dynamic methodname(dynamic input)
{
return input;
}
Input will be returned as the same type, and you do not need to call the method as a generic.
输入将作为相同类型返回，您不需要将方法作为泛型调用。
Reference:
https://msdn.microsoft.com/en-us/library/dd264736.aspx
