属性中的类型约束 [英] Type constraints in Attributes

问题描述

我想用自定义属性编写枚举，例如：

I want to write my enum with custom attributes, for example:

public enum SomeEnum: long
{
    [SomeAttribute<MyClass1>]
    Sms = 1,
    [SomeAttribute<MyClass2>]
    Email = 2
}

，但是属性不支持泛型。好吧，最相似的解决方案是：

but attributes doesn't support generics. Well, the most similar solution is:

public enum SomeEnum: long
{
    [SomeAttribute(typeof(MyClass1))]
    Sms = 1,
    [SomeAttribute(typeof(MyClass2))]
    Email = 2
}

这是问题：我想从 ICustomInterface <继承 Class1 / code>，因此可以使用泛型写约束：

And here is problem: I want Class1 to be inherited from ICustomInterface, so with generics I can write constraint:

[AttributeUsage(AttributeTargets.All)]
class SomeAttribute<T> : Attribute where T: ICustomInterface
{
}

但属性没有支持泛型。

所以最后一个问题是：如何检查该类型的编译时间（如 T 约束）

so finally question is: how can I check in compile time (like T constraints) that type is implementing some interface?

推荐答案

对最后一个问题很简单：

Very simple to your final question:

所以最后一个问题是：如何检查类型正在实现某些接口的编译时间（如T
约束）？

so finally question is: how can I check in compile time (like T constraints) that type is implementing some interface?

您不能这样做。

但是您可以在运行时使用一些反射方法来检查它，例如：
< a href = http://msdn.microsoft.com/de-de/library/system.type.isassignablefrom(v=vs.110).aspx rel = noreferrer> Type.IsAssignableFrom

But you can check it at runtime, with some reflection methods like: Type.IsAssignableFrom

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