Replace nested ForEach with Select if applicable

Question

Is it possible to replace method ForEach() usage with Select() or something else to write next code in one string with nested extension methods? OR maybe there are another ways to improve the algorithm?

var list = new List<IStatementParser>();

System.IO.Directory.GetFiles(path, "*.dll")
    .ForEach(f => System.Reflection.Assembly.LoadFrom(f)
     .GetTypes()
     .Where(t => !t.IsInterface && typeof(IFoo).IsAssignableFrom(t))
     .ForEach(t => list.Add((IFoo)Activator.CreateInstance(t))));

return list.ToDictionary(k => k.Name, v => v.GetType());

It loads all classes from assemblies in path that implements IFoo and adds them to Dictionary<string, Type> where string is IFoo.Name

Answer 1

I don't see any need for an intermediate List here at all - you can just do this:

return (from dll in Directory.GetFiles(path, "*.dll")
        let asm = Assembly.LoadFrom(dll)
        from t in asm.GetTypes()
        where !t.IsInterface && typeof(IFoo).IsAssignableFrom(t)
        select (IFoo)Activator.CreateInstance(t)
       ).ToDictionary(foo => foo.Name, foo => foo.GetType())

By the way, you might also want to check whether a type is abstract before trying to instantiate it.

Answer 2

var foos =
    from dllFile in Directory.GetFiles(path, "*.dll")
    from type in Assembly.LoadFrom(dllFile).GetTypes()
    where !type.IsInterface && typeof(IFoo).IsAssignableFrom(type)
    select (IFoo) Activator.CreateInstance(type);

return foos.ToDictionary(foo => foo.Name, foo => foo.GetType());