Why in c# can't we wrap anonymous objects in list of objects?

Question

Why in c# can't we wrap anonymous objects in list of objects? For Example I have seen this Question in StackOverFlow C# Linq, object definition does not contains a property

var anynomousObject = new { Amount = 10, weight = 20 };

List<object> ListOfAnynomous = new List<object> { anynomousObject, anynomousObject };
var productQuery =
            from prod in ListOfAnynomous
            select new { prod.Amount, prod.weight };

foreach (var v in productQuery)
{
    Console.WriteLine(v.Amount);
    Console.WriteLine(v.weight);
}

and the answer was that he should wrap the anonymous in list of dynamic but actually I can't understand why in the run time we can't get their values.

how exactly you wrapped the anonymous in list of dynamic? I've just made a simple test and looks like from dynamic prod in ... works. — Hopeless
– Hopeless, Commented Aug 9, 2015 at 9:27

Matías Fidemraizer · Accepted Answer · 2015-08-09 09:30:48Z

Anonymous types are also types and they're compiled into actual classes. That is, anonymous doesn't mean untyped.

If you add anonymous type instances to a List<object> you're upcasting them to object and you lose the typing itself, thus, you can't access anonymous type instance properties.

Instead of storing them in a List<dynamic>, you should go with other solution: store in a generic list of anonymous type. Since you don't gain access to anonymous type names (it's anonymous, they've no name - well, they compile into actual classes, but this is how internally works at compile/run time, it's a low-level detail), you can't use explicit typing, but C# has type-inferred variables:

// compiles to string a = "hello"; assignment defines the type
var a = "hello";

...so, what about this?

// Use a type-inferred array to define the items and then convert the array
// to list!
// Now you can use each anonymous type instance properties in LINQ ;)
var listOfAnonymousInstances = new [] { new { Amount = 10, weight = 20 } }.ToList();
// If you mouse over the var keyword, you'll find that it's a List<a`>!

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