Can a class property/field be of anonymous type in C# 4.0?

Question

As in:

public class MyClass {

  private static var MyProp = new {item1 = \"a\", item2 = \"b\"};

}

Note: The above doesn\'t compile nor wo

Answer 1

In C# 7 you can finally do this:

private (string Login, string Password) _credentials = (Login: "123", Password: "123");

Answer 2

No, anonymous types cannot be exposed outside of their declaring function as anything other than object. While the anonymous type is just syntactical sugar and does, in fact, create a concrete type, this type is never known (nor available) to the developer, and thus can't be used.

Answer 3

It sounds like you could be asking one or two questions so I'll try and address them both.

Can a class field be strongly typed to an anonymous type

No. Anonymous type names cannot be stated in C# code (hence anonymous). The only way to statically type them is

1. Generic type inferencee
2. Use of the var keyword

Neither of these are applicable to the field of a type.

Can a class field be initialized with an anonymous type expression?

Yes. The field just needs to be declared to a type compatible with anonymous types: object for example

public class MyClass { 
  private static object MyProp = new {item1 = "a", item2 = "b"}; 
} 

Answer 4

If this is C# 4, look into the dynamic keyword.

public class MyClass 
{ 
  private static dynamic MyProp = new {item1 = "a", item2 = "b"}; 
} 

However, as soon as you do this you lose any sort of type-safety and handy compiler checks.

Answer 5

How about using Tuple<string, string> instead?

public class MyClass {

  private static Tuple<string, string> MyProp = Tuple.Create("a", "b");

}

Answer 6

An property (or field) of a named class can't have an anonymous type, because such a type can't be referred to in code. However, an anonymous type can contain properties of anonymous type:

var myObj = new
{
    Foo = new { Name = "Joe", Age = 20 }
};

But such a construct has no practical use outside the local scope...