Instantiate a class from its textual name

Question

Don't ask me why but I need to do the following:

string ClassName = "SomeClassName";   object o = MagicallyCreateInstance("SomeClassName"); 

I want to know how many ways there are to do this is and which approach to use in which scenario.

Examples:

• Activator.CreateInstance
• Assembly.GetExecutingAssembly.CreateInstance("")
• Any other suggestions would be appreciated

This question is not meant to be an open ended discussion because I am sure there are only so many ways this can be achieved.

Answer 1

Here's what the method may look like:

private static object MagicallyCreateInstance(string className) {     var assembly = Assembly.GetExecutingAssembly();      var type = assembly.GetTypes()         .First(t => t.Name == className);      return Activator.CreateInstance(type); } 

The code above assumes that:

• you are looking for a class that is in the currently executing assembly (this can be adjusted - just change assembly to whatever you need)
• there is exactly one class with the name you are looking for in that assembly
• the class has a default constructor

Update:

Here's how to get all the classes that derive from a given class (and are defined in the same assembly):

private static IEnumerable<Type> GetDerivedTypesFor(Type baseType) {     var assembly = Assembly.GetExecutingAssembly();      return assembly.GetTypes()         .Where(baseType.IsAssignableFrom)         .Where(t => baseType != t); }