C#: Reflection Tips

C# is a very powerful language. However for this "powerful" perspective, there are various way to achieve something and you might hover among which way to take (at least for me :D).
In this post I will focus on "Reflection" and introduce some small code spinets.

First we assume this trivial class is defined in Utility assembly.

namespace Utility.Sample
{
    public class Target
    {

        public string wrapByDoubleQuote(string text)
        {
            return "\"" + text + "\"";
        }
    }
}

Get Type from String and Instantiate by Activator

// type from reflection
Type type = Type.GetType("Utility.Sample.Target");

// instantiate object from Type
Target target = Activator.CreateInstance(type) as Target;
            
// invoke method normally
Console.WriteLine(target.wrapByDoubleQuote("contents"));

Instantiate Object from ConstructorInfo and Invoke Method by Reflection

// type from reflection
// or you can do typeof(Target);
Type type = Type.GetType("Utility.Sample.Target");

// another way to instantiate object. Using ConstructorInfo!!
ConstructorInfo constructor = type.GetConstructor(Type.EmptyTypes);
object target = constructor.Invoke(new object[] { });


// Get method object
MethodInfo method = type.GetMethod("wrapByDoubleQuote");

// target type doesn't have to be Target class
// invoke method reflectively
Console.WriteLine(method.Invoke(target, new object[] {"contents"}));

Instantiate Object via ObjectHandle

// first argument is assembly name, 2nd argument is full class name
ObjectHandle handle = Activator.CreateInstance("Utility", "Utility.Sample.Target");

Target target = handle.Unwrap() as Target;

Console.WriteLine(target.wrapByDoubleQuote("contents"));

Instantiate Object From Assembly

// see defined method below
Target target = CreateInstanceFromAssembly<Target>("Utility", "Utility.Sample.Target");

Console.WriteLine(target.wrapByDoubleQuote("contents"));

private static T CreateInstanceFromAssembly<T>(string assembly, string typeName) where T : class
{
    var name = new AssemblyName(assembly);
    var asm = Assembly.Load(name);
    return asm.CreateInstance(typeName) as T;
}