Beginnings of simple one dependency injection. For: https://github.com/aeroson/mcs-ICodeCompiler/issues/6

DependencyAttribute.cs

using System;

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false, Inherited = true)]
public class DependencyAttribute : Attribute
{
}

DependencyManager.cs

using System.Collections.Generic;
using System.Reflection;
using System.Linq;
using System.Collections;
using System;

public class DependencyManager
{

	HashSet<object> instances = new HashSet<object>();
	HashSet<Type> registeredTypes = new HashSet<Type>();

	public void Register(params object[] instances)
	{
		foreach (var instance in instances)
		{
			instances.Add(instance);
		}
	}
	public void Register<T>(T instance)
	{
		Register(instance);
	}

	public void RegisterType<TManager>() where TManager : new()
	{
		registeredTypes.Add(typeof(TManager));
	}

	/// <summary>
	/// Get instance of  type
	/// </summary>
	/// <param name="type"></param>
	/// <returns></returns>
	public object GetInstance(Type type)
	{
		object instance = instances.FirstOrDefault(i =>
		{
			var t = i.GetType();
			return
				t == type ||
				t.IsSubclassOf(type) ||
				t.GetInterfaces().Contains(type);
		});
		if (instance == null)
		{
			var typeToInstantiate = registeredTypes.FirstOrDefault(t =>
				t == type ||
				t.IsSubclassOf(type) ||
				t.GetInterfaces().Contains(type)
			);
			if (typeToInstantiate == null)
			{
				throw new Exception("no registered type or instance found for " + type);
			}
			instance = Activator.CreateInstance(typeToInstantiate);
			Resolve(instance);
			Register(instance);				
		}
		return instance;
	}


	/// <summary>
	/// Assignes instances to members that are null and marked with DependencyAttribute, 
	/// </summary>
	/// <param name="instance"></param>
	public void Resolve(object instance)
	{
		var members = instance.GetType().GetMembers(
			BindingFlags.Instance |
			BindingFlags.Public | BindingFlags.NonPublic |
			BindingFlags.GetProperty | BindingFlags.SetProperty |
			BindingFlags.FlattenHierarchy
		).Where(m => m.GetCustomAttributes(typeof(DependencyAttribute), true) != null);
		foreach(var member in members)
		{				
			var prop = member as PropertyInfo;
			var field = member as FieldInfo;
			if (prop != null)
			{
				if (prop.GetValue(instance, null) == null)
				{
					var resolvedMemberValue = GetInstance(member.ReflectedType);
					prop.SetValue(instance, resolvedMemberValue, null);
				}
			}
			if (field != null)
			{
				if (field.GetValue(instance) == null)
				{
					var resolvedMemberValue = GetInstance(member.ReflectedType);
					field.SetValue(instance, resolvedMemberValue);
				}
			}
		}

	}

	/// <summary>
	/// Creates new instance and then resolves it's dependencies.
	/// </summary>
	/// <typeparam name="T"></typeparam>
	/// <returns></returns>
	public T Resolve<T>() where T : new()
	{
		var ret = new T();
		Resolve(ret);
		return ret;
	}

}