在C＃3.5中获取类型参数受约束的类的类型

Question

I'm trying to get the type of a custom class to which I don't have access to editing and it has a parameter type constraint on its declaration. Just like this:

public class GenericItemCollection<T> where T : System.IEquatable<T>
{
    public GenericItemCollection();
    public GenericItemCollection(string json);

    public int Count { get; }
    public List<T> Created { get; }
    public List<T> Current { get; }
    public List<T> Deleted { get; }
    public List<T> Original { get; }
    public List<T> Updated { get; }

    public void AcceptChanges();
    public void AddItem(T item);
    public void BindItem(T item);
    public void DeleteItem(T item);
    public void UpdateItem(T item);
}

}

So what I want is the type GenericItemCollection when T is actually something. Ie:

private void MyMethod<T>(GenericItemCollection<T> genericList){
    Type listType = typeof(GenericItemCollection<typeof(T)>);
    //...
}

which will be called as such:

MyMethod<Foo>(fooGenericList);
MyMethod<Bar>(barGenericList);

In that case, I want listType to be

GenericItemCollection<Foo> 

and

GenericItemCollection<Bar> 

I know typeof(T) won't exist before runtime but it should return a Type regardless but VS just says "Type expected" on

GenericItemCollection<typeof(T)> 

I'm not all that proficient using Generics, so I'm obviously missing something and I'd like you guys to point out what that is. Many thanks.

Answer 1

First of, whatever constraint is applied to the generic type parameter of GenericItemCollection must also be applied to the generic type parameter of MyMethod

private void MyMethod<T>(GenericItemCollection<T> genericList) where T: IEquatable<T>

Then, just replace typeof(T) with T

Type listType = typeof(GenericItemCollection<T>);