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Anton Wieslander
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dependency injection
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3 files changed

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‎Dependency Injection/activator.linq

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<Query Kind="Program" />
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void Main()
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{
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// var service = new HelloService();
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// var consumer = new ServiceConsumer(service);
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var a = typeof(HelloService).Dump();
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var service = (HelloService) Activator.CreateInstance(typeof(HelloService));
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var consumer = (ServiceConsumer) Activator.CreateInstance(typeof(ServiceConsumer), service);
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service.Print();
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consumer.Print();
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}
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public class ServiceConsumer
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{
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HelloService _hello;
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public ServiceConsumer(HelloService hello)
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{
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_hello= hello;
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}
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public void Print()
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{
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_hello.Print();
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}
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}
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public class HelloService
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{
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public void Print(){
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"Hello World".Dump();
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}
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}

‎Dependency Injection/lifetimes.linq

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<Query Kind="Program" />
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void Main()
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{
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var container = new DependencyContainer();
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container.AddTransient<ServiceConsumer>();
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container.AddTransient<HelloService>();
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container.AddSingleton<MessageService>();
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var resolver = new DependencyResolver(container);
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var service1 = resolver.GetService<ServiceConsumer>();
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service1.Print();
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var service2 = resolver.GetService<ServiceConsumer>();
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service2.Print();
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var service3 = resolver.GetService<ServiceConsumer>();
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service3.Print();
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}
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public class DependencyResolver
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{
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DependencyContainer _container;
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public DependencyResolver(DependencyContainer container)
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{
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_container = container;
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}
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public T GetService<T>()
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{
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return (T)GetService(typeof(T));
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}
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public object GetService(Type type)
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{
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var dependency = _container.GetDependency(type);
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var constructor = dependency.Type.GetConstructors().Single();
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var parameters = constructor.GetParameters().ToArray();
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if (parameters.Length > 0)
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{
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var parameterImplementations = new object[parameters.Length];
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for (int i = 0; i < parameters.Length; i++)
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{
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parameterImplementations[i] = GetService(parameters[i].ParameterType);
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}
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return CreateImplementaiton(dependency, t => Activator.CreateInstance(t, parameterImplementations));
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}
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return CreateImplementaiton(dependency, t => Activator.CreateInstance(t));
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}
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public object CreateImplementaiton(Dependency dependency, Func<Type, object> factory)
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{
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if (dependency.Implemented)
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{
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return dependency.Implementation;
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}
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var implementation = factory(dependency.Type);
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if (dependency.Lifetime == DependencyLifetime.Singleton)
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{
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dependency.AddImplementation(implementation);
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}
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return implementation;
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}
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}
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public class DependencyContainer
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{
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List<Dependency> _dependencies;
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public DependencyContainer()
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{
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_dependencies = new List<Dependency>();
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}
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public void AddSingleton<T>()
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{
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_dependencies.Add(new Dependency(typeof(T), DependencyLifetime.Singleton));
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}
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public void AddTransient<T>()
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{
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_dependencies.Add(new Dependency(typeof(T), DependencyLifetime.Transient));
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}
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public Dependency GetDependency(Type type)
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{
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return _dependencies.First(x => x.Type.Name == type.Name);
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}
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}
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public class Dependency
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{
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public Dependency(Type t, DependencyLifetime l)
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{
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Type = t;
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Lifetime = l;
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}
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public Type Type { get; set; }
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public DependencyLifetime Lifetime { get; set; }
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public object Implementation { get; set; }
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public bool Implemented { get; set; }
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public void AddImplementation(object i){
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Implementation = i;
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Implemented = true;
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}
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}
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public enum DependencyLifetime
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{
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Singleton = 0,
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Transient = 1,
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}
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public class ServiceConsumer
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{
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HelloService _hello;
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public ServiceConsumer(HelloService hello)
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{
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_hello = hello;
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}
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public void Print()
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{
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_hello.Print();
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}
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}
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public class HelloService
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{
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MessageService _message;
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int _random;
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public HelloService(MessageService message)
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{
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_message = message;
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_random = new Random().Next();
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}
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public void Print()
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{
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$"Hello #{_random} World {_message.Message()}".Dump();
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}
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}
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public class MessageService
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{
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int _random;
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public MessageService()
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{
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_random = new Random().Next();
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}
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public string Message()
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{
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return $"Yo #{_random}";
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}
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}

‎Dependency Injection/resolver_container.linq

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<Query Kind="Program" />
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void Main()
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{
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//typeof(ServiceConsumer)
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// .GetConstructors()
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// .Select(x => x.GetParameters()).Dump();
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var container = new DependencyContainer();
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container.AddDependency(typeof(HelloService));
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container.AddDependency<ServiceConsumer>();
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container.AddDependency<MessageService>();
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var resolver = new DependencyResolver(container);
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var service = resolver.GetService<ServiceConsumer>();
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service.Print();
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}
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public class DependencyResolver
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{
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DependencyContainer _container;
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public DependencyResolver(DependencyContainer container)
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{
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_container = container;
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}
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public T GetService<T>()
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{
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return (T) GetService(typeof(T));
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}
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public object GetService(Type type)
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{
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var dependency = _container.GetDependency(type);
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var constructor = dependency.GetConstructors().Single();
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var parameters = constructor.GetParameters().ToArray();
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if (parameters.Length > 0)
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{
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var parameterImplementations = new object[parameters.Length];
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for (int i = 0; i < parameters.Length; i++)
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{
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parameterImplementations[i] = GetService(parameters[i].ParameterType);
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}
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return Activator.CreateInstance(dependency, parameterImplementations);
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}
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return Activator.CreateInstance(dependency);
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}
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}
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public class DependencyContainer
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{
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List<Type> _dependencies;
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public void AddDependency(Type type)
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{
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_dependencies = new List<Type>();
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_dependencies.Add(type);
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}
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public void AddDependency<T>()
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{
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_dependencies.Add(typeof(T));
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}
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public Type GetDependency(Type type)
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{
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return _dependencies.First(x => x.Name == type.Name);
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}
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}
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public class ServiceConsumer
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{
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HelloService _hello;
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public ServiceConsumer(HelloService hello)
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{
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_hello = hello;
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}
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public void Print()
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{
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_hello.Print();
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}
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}
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public class HelloService
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{
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MessageService _message;
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public HelloService(MessageService message)
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{
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_message = message;
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}
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public void Print()
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{
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$"Hello World {_message.Message()}".Dump();
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}
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}
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public class MessageService
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{
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public string Message()
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{
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return "Yo";
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}
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}

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