反映具有约束的泛型类型的所有可能排列(Reflect all possible permutations of a generic type with constraints)

给定具有约束的泛型类型：

class MyClass<T> where T: Alpha { }

和约束的实现：

class Alpha {} class Bravo : Alpha {} class Charlie : Alpha {}

如何在运行时获得所有组合的泛型类型？

// I want these types at run-time MyClass<Alpha> MyClass<Bravo> MyClass<Charlie>

编辑：根据@ rich.okelly的回答，我认为真正的问题是：

如何在运行时找到实现我的泛型类型约束的所有类型？

所以，如果我给了typeof(MyClass<>) ，我会得到上面的类型。

Given a generic type with constraints:

class MyClass<T> where T: Alpha { }

and implementations of that constraint:

class Alpha {} class Bravo : Alpha {} class Charlie : Alpha {}

How can get generic types for all the combinations at run-time?

// I want these types at run-time MyClass<Alpha> MyClass<Bravo> MyClass<Charlie>

EDIT: Based on @rich.okelly's answer, I think the real question is this:

How can I find all the types that implement my generic type's constraint at run-time?

So if I'm given typeof(MyClass<>), I get the types above.

最满意答案

就像是：

var alphaType = typeof(Alpha); var allTypes = AppDomain.CurrentDomain.GetAssemblies().SelectMany(a => a.GetTypes()).Where(t => alphaType.IsAssignableFrom(t)); var myClass = typeof(MyClass<>); foreach (var type in allTypes) { var genericType = myClass.MakeGenericType(type); }

或者，如果已经加载了泛型类型：

var allTypes = AppDomain.CurrentDomain.GetAssemblies().SelectMany(a => a.GetTypes()).Where(t => t.IsGenericType && t.GetGenericTypeDefinition() == typeof(MyClass<>)); foreach (var type in allTypes) { ... }

更新

您可以使用GetGenericArguments()方法和GetGenericParameterConstraints()方法来获取所需的类型。

var myType = typeof(MyClass<>); var typeConstraints = myType.GetGenericArguments().First().GetGenericParameterConstraints(); var allTypes = AppDomain.CurrentDomain.GetAssemblies().SelectMany(a => a.GetTypes()); var genericTypes = allTypes.Where(t => typeConstraints.All(tc => tc.IsAssignableFrom(t))).Select(t => myType.MakeGenericType(t)); foreach (var type in genericTypes) { ... }

Something like:

var alphaType = typeof(Alpha); var allTypes = AppDomain.CurrentDomain.GetAssemblies().SelectMany(a => a.GetTypes()).Where(t => alphaType.IsAssignableFrom(t)); var myClass = typeof(MyClass<>); foreach (var type in allTypes) { var genericType = myClass.MakeGenericType(type); }

Alternatively, if the generic types have already been loaded:

var allTypes = AppDomain.CurrentDomain.GetAssemblies().SelectMany(a => a.GetTypes()).Where(t => t.IsGenericType && t.GetGenericTypeDefinition() == typeof(MyClass<>)); foreach (var type in allTypes) { ... }

Update

You can use the GetGenericArguments() method and the GetGenericParameterConstraints() method to get the required types.

var myType = typeof(MyClass<>); var typeConstraints = myType.GetGenericArguments().First().GetGenericParameterConstraints(); var allTypes = AppDomain.CurrentDomain.GetAssemblies().SelectMany(a => a.GetTypes()); var genericTypes = allTypes.Where(t => typeConstraints.All(tc => tc.IsAssignableFrom(t))).Select(t => myType.MakeGenericType(t)); foreach (var type in genericTypes) { ... }

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