为什么C＃不允许匿名转换为对象？

Question

I would like to know the reason that does not allow this type of convertion. The subject was already approached in this post in SO , but I want the low level explanation on why this is not possible natively.

Why does these casts fail?

OBS: I know it is possible to do so by reflection.

IList<People> peopleList = new List<People>()
{
    new People() { Name = "Again", Age = 10 },
    new People() { Name = "Over", Age = 20 },
    new People() { Name = "Jonh", Age = 30 },
    new People() { Name = "Enzo", Age = 40 },
};

var anonymous = (from p in peopleList
                select new
                {
                    Name = p.Name,
                    Age = p.Age
                });

// Does not work
IList<People> listt = (IList<People>)anonymous; 
//Does not Work
IList<People> listt = (anonymous as List<People>);

Answer 1

The question is why anonymous cannot be successfully cast to IList<People> or List<People> .

• The value of the query expression is an object that can execute the query . It is not the result set of a query execution. anonymous implements IEnumerable<T> , not IList<T> and certainly it does not subtype List<T> . So it cannot be cast to any IList<T> or List<T> type. If that's what you want then use ToList() to execute the query and store the result set in a list.
• Can the query be cast to IEnumerable<People> ? No. It is a sequence of anonymously-typed objects that have copied some of the values associated with a People . So it is a sequence of anonymous objects, not a sequence of people.

I note also that in new C# 7 code it's a better practice to use tuples instead of anonymous types if you can in your application. They have better support in the type system and produce less collection pressure.