Activators — Dotnet 4.6.1

In the era of .NET 4.6.1, the Activator class acted as the universal mechanic. It was the tool the runtime used to bridge the gap between "knowing of a type" and "having an instance of that type."

The most common method in this story is Activator.CreateInstance.

Here is how the story plays out in code: activators dotnet 4.6.1

When Activator.CreateInstance is called, the .NET runtime:

Early DI frameworks or custom containers used Activator.CreateInstance to resolve services dynamically. In the era of

Example – dynamic type instantiation (works only if 4.6.1 is the target runtime):

using System;
public class Sample
public void SayHello() => Console.WriteLine("Activated in .NET 4.6.1");
 class Program
static void Main()
Type type = Type
class Program
static void Main()
Type type = Type.GetType("Sample");
object instance = Activator.CreateInstance(type);
((Sample)instance).SayHello();

public static ObjectActivator CreateActivator(ConstructorInfo ctor)
var paramExpr = Expression.Parameter(typeof(object[]), "args");
    var argExprs = ctor.GetParameters().Select((p, i) =>
        Expression.Convert(Expression.ArrayIndex(paramExpr, Expression.Constant(i)), p.ParameterType));
    var newExpr = Expression.New(ctor, argExprs);
    var lambda = Expression.Lambda<Func<object[], object>>(newExpr, paramExpr);
    return lambda.Compile();