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• Creating a dynamic proxy generator with c# – Part 4 – Calling the base method

  - by SeanMcAlinden

  Creating a dynamic proxy generator with c# – Part 1 – Creating the Assembly builder, Module builder and caching mechanism Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design Creating a dynamic proxy generator with c# – Part 3 – Creating the constructors   The plan for calling the base methods from the proxy is to create a private method for each overridden proxy method, this will allow the proxy to use a delegate to simply invoke the private method when required. Quite a few helper classes have been created to make this possible so as usual I would suggest download or viewing the code at http://rapidioc.codeplex.com/. In this post I’m just going to cover the main points for when creating methods. Getting the methods to override The first two notable methods are for getting the methods. private static MethodInfo[] GetMethodsToOverride<TBase>() where TBase : class {     return typeof(TBase).GetMethods().Where(x =>         !methodsToIgnore.Contains(x.Name) &&                              (x.Attributes & MethodAttributes.Final) == 0)         .ToArray(); } private static StringCollection GetMethodsToIgnore() {     return new StringCollection()     {         "ToString",         "GetHashCode",         "Equals",         "GetType"     }; } The GetMethodsToIgnore method string collection contains an array of methods that I don’t want to override. In the GetMethodsToOverride method, you’ll notice a binary AND which is basically saying not to include any methods marked final i.e. not virtual. Creating the MethodInfo for calling the base method This method should hopefully be fairly easy to follow, it’s only function is to create a MethodInfo which points to the correct base method, and with the correct parameters. private static MethodInfo CreateCallBaseMethodInfo<TBase>(MethodInfo method) where TBase : class {     Type[] baseMethodParameterTypes = ParameterHelper.GetParameterTypes(method, method.GetParameters());       return typeof(TBase).GetMethod(        method.Name,        BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,        null,        baseMethodParameterTypes,        null     ); }   /// <summary> /// Get the parameter types. /// </summary> /// <param name="method">The method.</param> /// <param name="parameters">The parameters.</param> public static Type[] GetParameterTypes(MethodInfo method, ParameterInfo[] parameters) {     Type[] parameterTypesList = Type.EmptyTypes;       if (parameters.Length > 0)     {         parameterTypesList = CreateParametersList(parameters);     }     return parameterTypesList; }   Creating the new private methods for calling the base method The following method outline how I’ve created the private methods for calling the base class method. private static MethodBuilder CreateCallBaseMethodBuilder(TypeBuilder typeBuilder, MethodInfo method) {     string callBaseSuffix = "GetBaseMethod";       if (method.IsGenericMethod || method.IsGenericMethodDefinition)     {                         return MethodHelper.SetUpGenericMethod             (                 typeBuilder,                 method,                 method.Name + callBaseSuffix,                 MethodAttributes.Private | MethodAttributes.HideBySig             );     }     else     {         return MethodHelper.SetupNonGenericMethod             (                 typeBuilder,                 method,                 method.Name + callBaseSuffix,                 MethodAttributes.Private | MethodAttributes.HideBySig             );     } } The CreateCallBaseMethodBuilder is the entry point method for creating the call base method. I’ve added a suffix to the base classes method name to keep it unique. Non Generic Methods Creating a non generic method is fairly simple public static MethodBuilder SetupNonGenericMethod(     TypeBuilder typeBuilder,     MethodInfo method,     string methodName,     MethodAttributes methodAttributes) {     ParameterInfo[] parameters = method.GetParameters();       Type[] parameterTypes = ParameterHelper.GetParameterTypes(method, parameters);       Type returnType = method.ReturnType;       MethodBuilder methodBuilder = CreateMethodBuilder         (             typeBuilder,             method,             methodName,             methodAttributes,             parameterTypes,             returnType         );       ParameterHelper.SetUpParameters(parameterTypes, parameters, methodBuilder);       return methodBuilder; }   private static MethodBuilder CreateMethodBuilder (     TypeBuilder typeBuilder,     MethodInfo method,     string methodName,     MethodAttributes methodAttributes,     Type[] parameterTypes,     Type returnType ) { MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, methodAttributes, returnType, parameterTypes); return methodBuilder; } As you can see, you simply have to declare a method builder, get the parameter types, and set the method attributes you want.   Generic Methods Creating generic methods takes a little bit more work. /// <summary> /// Sets up generic method. /// </summary> /// <param name="typeBuilder">The type builder.</param> /// <param name="method">The method.</param> /// <param name="methodName">Name of the method.</param> /// <param name="methodAttributes">The method attributes.</param> public static MethodBuilder SetUpGenericMethod     (         TypeBuilder typeBuilder,         MethodInfo method,         string methodName,         MethodAttributes methodAttributes     ) {     ParameterInfo[] parameters = method.GetParameters();       Type[] parameterTypes = ParameterHelper.GetParameterTypes(method, parameters);       MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName,         methodAttributes);       Type[] genericArguments = method.GetGenericArguments();       GenericTypeParameterBuilder[] genericTypeParameters =         GetGenericTypeParameters(methodBuilder, genericArguments);       ParameterHelper.SetUpParameterConstraints(parameterTypes, genericTypeParameters);       SetUpReturnType(method, methodBuilder, genericTypeParameters);       if (method.IsGenericMethod)     {         methodBuilder.MakeGenericMethod(genericArguments);     }       ParameterHelper.SetUpParameters(parameterTypes, parameters, methodBuilder);       return methodBuilder; }   private static GenericTypeParameterBuilder[] GetGenericTypeParameters     (         MethodBuilder methodBuilder,         Type[] genericArguments     ) {     return methodBuilder.DefineGenericParameters(GenericsHelper.GetArgumentNames(genericArguments)); }   private static void SetUpReturnType(MethodInfo method, MethodBuilder methodBuilder, GenericTypeParameterBuilder[] genericTypeParameters) {     if (method.IsGenericMethodDefinition)     {         SetUpGenericDefinitionReturnType(method, methodBuilder, genericTypeParameters);     }     else     {         methodBuilder.SetReturnType(method.ReturnType);     } }   private static void SetUpGenericDefinitionReturnType(MethodInfo method, MethodBuilder methodBuilder, GenericTypeParameterBuilder[] genericTypeParameters) {     if (method.ReturnType == null)     {         methodBuilder.SetReturnType(typeof(void));     }     else if (method.ReturnType.IsGenericType)     {         methodBuilder.SetReturnType(genericTypeParameters.Where             (x => x.Name == method.ReturnType.Name).First());     }     else     {         methodBuilder.SetReturnType(method.ReturnType);     }             } Ok, there are a few helper methods missing, basically there is way to much code to put in this post, take a look at the code at http://rapidioc.codeplex.com/ to follow it through completely. Basically though, when dealing with generics there is extra work to do in terms of getting the generic argument types setting up any generic parameter constraints setting up the return type setting up the method as a generic All of the information is easy to get via reflection from the MethodInfo.   Emitting the new private method Emitting the new private method is relatively simple as it’s only function is calling the base method and returning a result if the return type is not void. ILGenerator il = privateMethodBuilder.GetILGenerator();   EmitCallBaseMethod(method, callBaseMethod, il);   private static void EmitCallBaseMethod(MethodInfo method, MethodInfo callBaseMethod, ILGenerator il) {     int privateParameterCount = method.GetParameters().Length;       il.Emit(OpCodes.Ldarg_0);       if (privateParameterCount > 0)     {         for (int arg = 0; arg < privateParameterCount; arg++)         {             il.Emit(OpCodes.Ldarg_S, arg + 1);         }     }       il.Emit(OpCodes.Call, callBaseMethod);       il.Emit(OpCodes.Ret); } So in the main method building method, an ILGenerator is created from the method builder. The ILGenerator performs the following actions: Load the class (this) onto the stack using the hidden argument Ldarg_0. Create an argument on the stack for each of the method parameters (starting at 1 because 0 is the hidden argument) Call the base method using the Opcodes.Call code and the MethodInfo we created earlier. Call return on the method   Conclusion Now we have the private methods prepared for calling the base method, we have reached the last of the relatively easy part of the proxy building. Hopefully, it hasn’t been too hard to follow so far, there is a lot of code so I haven’t been able to post it all so please check it out at http://rapidioc.codeplex.com/. The next section should be up fairly soon, it’s going to cover creating the delegates for calling the private methods created in this post.   Kind Regards, Sean.

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• Creating a dynamic proxy generator with c# – Part 3 – Creating the constructors

  - by SeanMcAlinden

  Creating a dynamic proxy generator with c# – Part 1 – Creating the Assembly builder, Module builder and caching mechanism Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design For the latest code go to http://rapidioc.codeplex.com/ When building our proxy type, the first thing we need to do is build the constructors. There needs to be a corresponding constructor for each constructor on the passed in base type. We also want to create a field to store the interceptors and construct this list within each constructor. So assuming the passed in base type is a User<int, IRepository> class, were looking to generate constructor code like the following:   Default Constructor public User`2_RapidDynamicBaseProxy() {     this.interceptors = new List<IInterceptor<User<int, IRepository>>>();     DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>();     this.interceptors.Add(item); }     Parameterised Constructor public User`2_RapidDynamicBaseProxy(IRepository repository1) : base(repository1) {     this.interceptors = new List<IInterceptor<User<int, IRepository>>>();     DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>();     this.interceptors.Add(item); }   As you can see, we first populate a field on the class with a new list of the passed in base type. Construct our DefaultInterceptor class. Add the DefaultInterceptor instance to our interceptor collection. Although this seems like a relatively small task, there is a fair amount of work require to get this going. Instead of going through every line of code – please download the latest from http://rapidioc.codeplex.com/ and debug through. In this post I’m going to concentrate on explaining how it works. TypeBuilder The TypeBuilder class is the main class used to create the type. You instantiate a new TypeBuilder using the assembly module we created in part 1. /// <summary> /// Creates a type builder. /// </summary> /// <typeparam name="TBase">The type of the base class to be proxied.</typeparam> public static TypeBuilder CreateTypeBuilder<TBase>() where TBase : class {     TypeBuilder typeBuilder = DynamicModuleCache.Get.DefineType         (             CreateTypeName<TBase>(),             TypeAttributes.Class | TypeAttributes.Public,             typeof(TBase),             new Type[] { typeof(IProxy) }         );       if (typeof(TBase).IsGenericType)     {         GenericsHelper.MakeGenericType(typeof(TBase), typeBuilder);     }       return typeBuilder; }   private static string CreateTypeName<TBase>() where TBase : class {     return string.Format("{0}_RapidDynamicBaseProxy", typeof(TBase).Name); } As you can see, I’ve create a new public class derived from TBase which also implements my IProxy interface, this is used later for adding interceptors. If the base type is generic, the following GenericsHelper.MakeGenericType method is called. GenericsHelper using System; using System.Reflection.Emit; namespace Rapid.DynamicProxy.Types.Helpers {     /// <summary>     /// Helper class for generic types and methods.     /// </summary>     internal static class GenericsHelper     {         /// <summary>         /// Makes the typeBuilder a generic.         /// </summary>         /// <param name="concrete">The concrete.</param>         /// <param name="typeBuilder">The type builder.</param>         public static void MakeGenericType(Type baseType, TypeBuilder typeBuilder)         {             Type[] genericArguments = baseType.GetGenericArguments();               string[] genericArgumentNames = GetArgumentNames(genericArguments);               GenericTypeParameterBuilder[] genericTypeParameterBuilder                 = typeBuilder.DefineGenericParameters(genericArgumentNames);               typeBuilder.MakeGenericType(genericTypeParameterBuilder);         }           /// <summary>         /// Gets the argument names from an array of generic argument types.         /// </summary>         /// <param name="genericArguments">The generic arguments.</param>         public static string[] GetArgumentNames(Type[] genericArguments)         {             string[] genericArgumentNames = new string[genericArguments.Length];               for (int i = 0; i < genericArguments.Length; i++)             {                 genericArgumentNames[i] = genericArguments[i].Name;             }               return genericArgumentNames;         }     } }       As you can see, I’m getting all of the generic argument types and names, creating a GenericTypeParameterBuilder and then using the typeBuilder to make the new type generic. InterceptorsField The interceptors field will store a List<IInterceptor<TBase>>. Fields are simple made using the FieldBuilder class. The following code demonstrates how to create the interceptor field. FieldBuilder interceptorsField = typeBuilder.DefineField(     "interceptors",     typeof(System.Collections.Generic.List<>).MakeGenericType(typeof(IInterceptor<TBase>)),       FieldAttributes.Private     ); The field will now exist with the new Type although it currently has no data – we’ll deal with this in the constructor. Add method for interceptorsField To enable us to add to the interceptorsField list, we are going to utilise the Add method that already exists within the System.Collections.Generic.List class. We still however have to create the methodInfo necessary to call the add method. This can be done similar to the following: Add Interceptor Field MethodInfo addInterceptor = typeof(List<>)     .MakeGenericType(new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) })     .GetMethod     (        "Add",        BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,        null,        new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) },        null     ); So we’ve create a List<IInterceptor<TBase>> type, then using the type created a method info called Add which accepts an IInterceptor<TBase>. Now in our constructor we can use this to call this.interceptors.Add(// interceptor); Building the Constructors This will be the first hard-core part of the proxy building process so I’m going to show the class and then try to explain what everything is doing. For a clear view, download the source from http://rapidioc.codeplex.com/, go to the test project and debug through the constructor building section. Anyway, here it is: DynamicConstructorBuilder using System; using System.Collections.Generic; using System.Reflection; using System.Reflection.Emit; using Rapid.DynamicProxy.Interception; using Rapid.DynamicProxy.Types.Helpers; namespace Rapid.DynamicProxy.Types.Constructors {     /// <summary>     /// Class for creating the proxy constructors.     /// </summary>     internal static class DynamicConstructorBuilder     {         /// <summary>         /// Builds the constructors.         /// </summary>         /// <typeparam name="TBase">The base type.</typeparam>         /// <param name="typeBuilder">The type builder.</param>         /// <param name="interceptorsField">The interceptors field.</param>         public static void BuildConstructors<TBase>             (                 TypeBuilder typeBuilder,                 FieldBuilder interceptorsField,                 MethodInfo addInterceptor             )             where TBase : class         {             ConstructorInfo interceptorsFieldConstructor = CreateInterceptorsFieldConstructor<TBase>();               ConstructorInfo defaultInterceptorConstructor = CreateDefaultInterceptorConstructor<TBase>();               ConstructorInfo[] constructors = typeof(TBase).GetConstructors();               foreach (ConstructorInfo constructorInfo in constructors)             {                 CreateConstructor<TBase>                     (                         typeBuilder,                         interceptorsField,                         interceptorsFieldConstructor,                         defaultInterceptorConstructor,                         addInterceptor,                         constructorInfo                     );             }         }           #region Private Methods           private static void CreateConstructor<TBase>             (                 TypeBuilder typeBuilder,                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ConstructorInfo defaultInterceptorConstructor,                 MethodInfo AddDefaultInterceptor,                 ConstructorInfo constructorInfo             ) where TBase : class         {             Type[] parameterTypes = GetParameterTypes(constructorInfo);               ConstructorBuilder constructorBuilder = CreateConstructorBuilder(typeBuilder, parameterTypes);               ILGenerator cIL = constructorBuilder.GetILGenerator();               LocalBuilder defaultInterceptorMethodVariable =                 cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase)));               ConstructInterceptorsField(interceptorsField, interceptorsFieldConstructor, cIL);               ConstructDefaultInterceptor(defaultInterceptorConstructor, cIL, defaultInterceptorMethodVariable);               AddDefaultInterceptorToInterceptorsList                 (                     interceptorsField,                     AddDefaultInterceptor,                     cIL,                     defaultInterceptorMethodVariable                 );               CreateConstructor(constructorInfo, parameterTypes, cIL);         }           private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL)         {             cIL.Emit(OpCodes.Ldarg_0);               if (parameterTypes.Length > 0)             {                 LoadParameterTypes(parameterTypes, cIL);             }               cIL.Emit(OpCodes.Call, constructorInfo);             cIL.Emit(OpCodes.Ret);         }           private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL)         {             for (int i = 1; i <= parameterTypes.Length; i++)             {                 cIL.Emit(OpCodes.Ldarg_S, i);             }         }           private static void AddDefaultInterceptorToInterceptorsList             (                 FieldBuilder interceptorsField,                 MethodInfo AddDefaultInterceptor,                 ILGenerator cIL,                 LocalBuilder defaultInterceptorMethodVariable             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Ldfld, interceptorsField);             cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable);             cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor);         }           private static void ConstructDefaultInterceptor             (                 ConstructorInfo defaultInterceptorConstructor,                 ILGenerator cIL,                 LocalBuilder defaultInterceptorMethodVariable             )         {             cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor);             cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable);         }           private static void ConstructInterceptorsField             (                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ILGenerator cIL             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor);             cIL.Emit(OpCodes.Stfld, interceptorsField);         }           private static ConstructorBuilder CreateConstructorBuilder(TypeBuilder typeBuilder, Type[] parameterTypes)         {             return typeBuilder.DefineConstructor                 (                     MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName                     | MethodAttributes.HideBySig, CallingConventions.Standard, parameterTypes                 );         }           private static Type[] GetParameterTypes(ConstructorInfo constructorInfo)         {             ParameterInfo[] parameterInfoArray = constructorInfo.GetParameters();               Type[] parameterTypes = new Type[parameterInfoArray.Length];               for (int p = 0; p < parameterInfoArray.Length; p++)             {                 parameterTypes[p] = parameterInfoArray[p].ParameterType;             }               return parameterTypes;         }           private static ConstructorInfo CreateInterceptorsFieldConstructor<TBase>() where TBase : class         {             return ConstructorHelper.CreateGenericConstructorInfo                 (                     typeof(List<>),                     new Type[] { typeof(IInterceptor<TBase>) },                     BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic                 );         }           private static ConstructorInfo CreateDefaultInterceptorConstructor<TBase>() where TBase : class         {             return ConstructorHelper.CreateGenericConstructorInfo                 (                     typeof(DefaultInterceptor<>),                     new Type[] { typeof(TBase) },                     BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic                 );         }           #endregion     } } So, the first two tasks within the class should be fairly clear, we are creating a ConstructorInfo for the interceptorField list and a ConstructorInfo for the DefaultConstructor, this is for instantiating them in each contructor. We then using Reflection get an array of all of the constructors in the base class, we then loop through the array and create a corresponding proxy contructor. Hopefully, the code is fairly easy to follow other than some new types and the dreaded Opcodes. ConstructorBuilder This class defines a new constructor on the type. ILGenerator The ILGenerator allows the use of Reflection.Emit to create the method body. LocalBuilder The local builder allows the storage of data in local variables within a method, in this case it’s the constructed DefaultInterceptor. Constructing the interceptors field The first bit of IL you’ll come across as you follow through the code is the following private method used for constructing the field list of interceptors. private static void ConstructInterceptorsField             (                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ILGenerator cIL             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor);             cIL.Emit(OpCodes.Stfld, interceptorsField);         } The first thing to know about generating code using IL is that you are using a stack, if you want to use something, you need to push it up the stack etc. etc. OpCodes.ldArg_0 This opcode is a really interesting one, basically each method has a hidden first argument of the containing class instance (apart from static classes), constructors are no different. This is the reason you can use syntax like this.myField. So back to the method, as we want to instantiate the List in the interceptorsField, first we need to load the class instance onto the stack, we then load the new object (new List<TBase>) and finally we store it in the interceptorsField. Hopefully, that should follow easily enough in the method. In each constructor you would now have this.interceptors = new List<User<int, IRepository>>(); Constructing and storing the DefaultInterceptor The next bit of code we need to create is the constructed DefaultInterceptor. Firstly, we create a local builder to store the constructed type. Create a local builder LocalBuilder defaultInterceptorMethodVariable =     cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase))); Once our local builder is ready, we then need to construct the DefaultInterceptor<TBase> and store it in the variable. Connstruct DefaultInterceptor private static void ConstructDefaultInterceptor     (         ConstructorInfo defaultInterceptorConstructor,         ILGenerator cIL,         LocalBuilder defaultInterceptorMethodVariable     ) {     cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor);     cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable); } As you can see, using the ConstructorInfo named defaultInterceptorConstructor, we load the new object onto the stack. Then using the store local opcode (OpCodes.Stloc), we store the new object in the local builder named defaultInterceptorMethodVariable. Add the constructed DefaultInterceptor to the interceptors field collection Using the add method created earlier in this post, we are going to add the new DefaultInterceptor object to the interceptors field collection. Add Default Interceptor private static void AddDefaultInterceptorToInterceptorsList     (         FieldBuilder interceptorsField,         MethodInfo AddDefaultInterceptor,         ILGenerator cIL,         LocalBuilder defaultInterceptorMethodVariable     ) {     cIL.Emit(OpCodes.Ldarg_0);     cIL.Emit(OpCodes.Ldfld, interceptorsField);     cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable);     cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor); } So, here’s whats going on. The class instance is first loaded onto the stack using the load argument at index 0 opcode (OpCodes.Ldarg_0) (remember the first arg is the hidden class instance). The interceptorsField is then loaded onto the stack using the load field opcode (OpCodes.Ldfld). We then load the DefaultInterceptor object we stored locally using the load local opcode (OpCodes.Ldloc). Then finally we call the AddDefaultInterceptor method using the call virtual opcode (Opcodes.Callvirt). Completing the constructor The last thing we need to do is complete the constructor. Complete the constructor private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL)         {             cIL.Emit(OpCodes.Ldarg_0);               if (parameterTypes.Length > 0)             {                 LoadParameterTypes(parameterTypes, cIL);             }               cIL.Emit(OpCodes.Call, constructorInfo);             cIL.Emit(OpCodes.Ret);         }           private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL)         {             for (int i = 1; i <= parameterTypes.Length; i++)             {                 cIL.Emit(OpCodes.Ldarg_S, i);             }         } So, the first thing we do again is load the class instance using the load argument at index 0 opcode (OpCodes.Ldarg_0). We then load each parameter using OpCode.Ldarg_S, this opcode allows us to specify an index position for each argument. We then setup calling the base constructor using OpCodes.Call and the base constructors ConstructorInfo. Finally, all methods are required to return, even when they have a void return. As there are no values on the stack after the OpCodes.Call line, we can safely call the OpCode.Ret to give the constructor a void return. If there was a value, we would have to pop the value of the stack before calling return otherwise, the method would try and return a value. Conclusion This was a slightly hardcore post but hopefully it hasn’t been too hard to follow. The main thing is that a number of the really useful opcodes have been used and now the dynamic proxy is capable of being constructed. If you download the code and debug through the tests at http://rapidioc.codeplex.com/, you’ll be able to create proxies at this point, they cannon do anything in terms of interception but you can happily run the tests, call base methods and properties and also take a look at the created assembly in Reflector. Hope this is useful. The next post should be up soon, it will be covering creating the private methods for calling the base class methods and properties. Kind Regards, Sean.

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• Connect ViewModel and View using Unity

  - by brainbox

  In this post i want to describe the approach of connecting View and ViewModel which I'm using in my last project.The main idea is to do it during resolve inside of unity container. It can be achived using InjectionFactory introduced in Unity 2.0 public static class MVVMUnityExtensions{    public static void RegisterView<TView, TViewModel>(this IUnityContainer container) where TView : FrameworkElement    {        container.RegisterView<TView, TView, TViewModel>();    }    public static void RegisterView<TViewFrom, TViewTo, TViewModel>(this IUnityContainer container)        where TViewTo : FrameworkElement, TViewFrom    {        container.RegisterType<TViewFrom>(new InjectionFactory(            c =>            {                var model = c.Resolve<TViewModel>();                var view = Activator.CreateInstance<TViewTo>();                view.DataContext = model;                return view;            }         ));    }}}And here is the sample how it could be used:var unityContainer = new UnityContainer();unityContainer.RegisterView<IFooView, FooView, FooViewModel>();IFooView view = unityContainer.Resolve<IFooView>(); // view with injected viewmodel in its datacontextPlease tell me your prefered way to connect viewmodel and view.

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• Oracle Unbreakable Enterprise Kernel and Emulex HBA Eliminate Silent Data Corruption

  - by sergio.leunissen

  Yesterday, Emulex announced that it has added support for T10 Protection Information (T10-PI), formerly called T10-DIF, to a number of its HBAs. When used with Oracle's Unbreakable Enterprise Kernel, this will prevent silent data corruption and help ensure the integrity and regulatory compliance of user data as it is transferred from the application to the SAN From the press release: Traditionally, protecting the integrity of customers' data has been done with multiple discrete solutions, including Error Correcting Code (ECC) and Cyclic Redundancy Check (CRC), but there have been coverage gaps across the I/O path from the operating system to the storage. The implementation of the T10-PI standard via Emulex's BlockGuard feature, in conjunction with other industry player's implementations, ensures that data is validated as it moves through the data path, from the application, to the HBA, to storage, enabling seamless end-to-end integrity. Read the white paper and don't miss the live webcast on eliminating silent data corruption on December 16th!

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• Announcing the RTM of MvcExtensions (aka System.Web.Mvc.Extensibility)

  - by kazimanzurrashid

  I am proud to announce the v1.0 of MvcExtensions (previously known as System.Web.Extensibility). There has been quite a few changes and enhancements since the last release. Some of the major changes are: The Namespace has been changed to MvcExtensions from System.Web.Mvc.Extensibility to avoid the unnecessary confusion that it is in the .NET Framework or part of the ASP.NET MVC. The Project is now moved to CodePlex from the GitHub. The primary reason to start the project over GitHub was distributed version control which is no longer valid as CodePlex recently added the Mercurial support. There is nothing wrong with GitHub, it is an excellent place for managing your project. But CodePlex has always been the native place for .NET project. MVC 1.0 support has been dropped. I will be covering each features in my blog, so stay tuned!!!

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• NHibernate Session DI from StructureMap in components

  - by Corey Coogan

  I know this is somewhat of a dead horse, but I'm not finding a satisfactory answer. First let me say, I am NOT dealing with a web app, otherwise managing NH Session is quite simple. I have a bunch of enterprise components. Those components have their own service layer that will act on multiple repositories. For example: Claim Component Claim Processing Service Claim Repository Billing Component Billing Service Billing REpository Policy Component PolicyLockService Policy Repository Now I may have a console, or windows application that needs to coordinate an operation that involves each of the services. I want to write the services to be injected with (DI) their required repositories. The Repositories should have an ISession, or similar, injected into them so that I can have this operation performed under one ISession/ITransaction. I'm aware of the Unit Of Work pattern and the many samples out there, but none of them showed DI. I'm also leery of [ThreadStatic] because this stuff can also be used from WCF and I have found enough posts describing how to do that. I've read about Business Conversations, but need something simple that each windows/console app can easily bootstrap since we have alot of these apps and some pretty inexperienced developers. So how can I configure StructureMap to inject the same ISession into each of the dependent repositories from an application? Here's a totally contrived and totally made up example without using SM (for clarification only - please don't spend energy critisizing): ConsoleApplication Main { using(ISession session = GetSession()) using(ITransaction trans = session.BeginTransaction()) { var policyRepo = new PolicyRepo(session); var policyService = new PolicyService(policyRepo); var billingRepo = new BillingRepo(session) var billingService = new BillingService(billingRepo); var claimRepo = new ClaimsRepo(session); var claimService = new ClaimService(claimRepo, policyService, billingService); claimService.FileCLaim(); trans.Commit(); } }

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• What's the difference between DI and factory patterns?

  - by Anthony Short

  I have a class which depends on 3 classes, all 3 of which have other classes they rely on. Currently, I'm using a container class to build up all the required classes, inject them into one another and return the application. The simplified version of the container looks something like this: class Builder { private $_options; public function __construct($options) { $this->_options = $options; } public function build() { $cache = $this->getCache(); $response = $this->getResponse(); $engine = $this->getEngine(); return new Application($cache,$response,$engine); } public function getResponse() { $encoder = $this->getResponseEncoder(); $cache = $this->getResponseCache(); return new Response($encoder,$cache); } // Methods for building each object } I'm not sure if this would be classified as FactoryMethod or a DI Container. They both seem to solve the same problem in the same way - They build objects and inject dependencies. This container has some more complicated building methods, like loading observers and attaching them to observable objects. Should factories be doing all the building (loading extensions etc) and the DI container should use these factories to inject dependencies? That way the sub-packages, like Cache, Response etc, can each have their own specialised factories.

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• How to configure non-admin accounts to install updates of non-microsoft applications using Active Di

  - by MadBoy

  How to configure non-admin users to allow them to install updates for Java and Adobe Acrobat Reader (or any other application which may need such privileges) without needing for administrator password on Windows 7. Updates for Microsoft products install without problems. This can be Active Directory (Windows 2003) solution, or computer based (employable through GPO or login script).

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• Hai mai pensato a quanto ti costa qualificare le tue opportunità commerciali?

  - by user812481

  Il successo delle attività di marketing è dovuto alla profonda conoscenza dei propri clienti: chi sono, cosa acquistano e perché, come preferiscono essere contattati. Se i dati sui clienti sono distribuiti su più sistemi, rispondere a queste domande diventa difficile ed oneroso. Hai bisogno di un mix di strumenti best-in-class per l'automazione della forza di vendita e per l'efficienza delle attività di marketing, facendo confluire i dati chiave in un unico punto di accesso, per una visione a 360 gradi dei clienti. Vorresti incrementare il ROI delle campagne di marketing, proponendo diversi messaggi in funzione dei differenti target, ottenendo così un maggior successo delle iniziative? Scopri come ottenere una conoscenza maggiore del target per creare campagne di successo, mirate e personalizzate, attraverso video in italiano e docuemtni da condividere con i vostri colleghi.

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• Unisciti alla Customer Experience Revolution! 27 settembre 2012, Milano

  - by antonella.buonagurio

  Si tiene giovedì 27 settembre a Milano Oracle Customer Experience Briefing, un evento pensato per riflettere sulla Customer Experience vista come strategia per dare vita a processi più completi ed innovativi per generare e gestire l’interazione con i consumatori, su tutti i canali. I lavori si terranno in particolare dalle 10.30 alle 13.00 presso Casa dell’Energia (Piazza Po 3). Enrico Finzi, Sociologo e Presidente di AstraRicerche, condividerà la propria visione sul tema e ne discuterà insieme agli esperti di Accenture e Oracle. L'incontro, rivolto in particolare alle aziende dei settori Retail e Beni di Consumo, consentirà dunque di comprendere perché la Customer Experience sia diventata la componente più importante e strategica del business delle imprese e di scoprire come essa accelleri l’acquisizione di nuovi clienti, incrementi la fidelizzazione ad un brand/prodotto/servizio, migliori l’efficienza operativa e sostenga le vendite. L’evento darà inoltre la possibilità di capire come le soluzioni di Customer Experience possono aiutare le aziende a far vivere questa esperienza ai clienti in modo coerente e personalizzato, attraverso tutti i canali e su tutti i dispositivi, ottenendo risultati misurabili.La partecipazione è gratuita su invito ed è riservata alle aziende finali. Per registrarsi all’evento è possibile collegarsi a questo link.

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• Woolrich Parka re elegante nel design e nella qualità

  - by WoolrichParka

  Il broker di sicurezza in teflon deve essere un fronte di nuovo leader della tecnologia nella nuova creazione di negozio outfits.Cool Woolrich Prezzi su internet dovrebbero essere le nuove gamme prossimi Woolrich qui che sono l'ideale per il vostro options.Not solo è resistente e ben protetto, con 625 oca completo potere bianco giù, ma il suo design famoso dispone anche Giubbotti Woolrich di una selezione altamente efficiente di tasche esterne, ideale per lo spazio di un facile deposito attrezzature e mano-warming.It è ben conosciuta dal mercato del design.wufengfengmaple36

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• Why is IoC / DI not common in Python?

  - by tux21b

  In Java IoC / DI is a very common practice which is extensively used in web applications, nearly all available frameworks and Java EE. On the other hand, there are also lots of big Python web applications, but beside of Zope (which I've heard should be really horrible to code) IoC doesn't seem to be very common in the Python world. (Please name some examples if you think that I'm wrong). There are of course several clones of popular Java IoC frameworks available for Python, springpython for example. But none of them seems to get used practically. At least, I've never stumpled upon a Django or sqlalchemy+<insert your favorite wsgi toolkit here> based web application which uses something like that. In my opinion IoC has reasonable advantages and would make it easy to replace the django-default-user-model for example, but extensive usage of interface classes and IoC in Python looks a bit odd and not »pythonic«. But maybe someone has a better explanation, why IoC isn't widely used in Python.

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• Calling DI Container directly in method code (MVC Actions)

  - by fearofawhackplanet

  I'm playing with DI (using Unity). I've learned how to do Constructor and Property injection. I have a static container exposed through a property in my Global.asax file (MvcApplication class). I have a need for a number of different objects in my Controller. It doesn't seem right to inject these throught the constructor, partly because of the high quantity of them, and partly because they are only needed in some Actions methods. The question is, is there anything wrong with just calling my container directly from within the Action methods? public ActionResult Foo() { IBar bar = (Bar)MvcApplication.Container.Resolve(IBar); // ... Bar uses a default constructor, I'm not actually doing any // injection here, I'm just telling my conatiner to give me Bar // when I ask for IBar so I can hide the existence of the concrete // Bar from my Controller. } This seems the simplest and most efficient way of doing things, but I've never seen an example used in this way. Is there anything wrong with this? Am I missing the concept in some way?

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• IoC/DI in the face of winforms and other generated code

  - by Kaleb Pederson

  When using dependency injection (DI) and inversion of control (IoC) objects will typically have a constructor that accepts the set of dependencies required for the object to function properly. For example, if I have a form that requires a service to populate a combo box you might see something like this: // my files public interface IDataService { IList<MyData> GetData(); } public interface IComboDataService { IList<MyComboData> GetComboData(); } public partial class PopulatedForm : BaseForm { private IDataService service; public PopulatedForm(IDataService service) { //... InitializeComponent(); } } This works fine at the top level, I just use my IoC container to resolve the dependencies: var form = ioc.Resolve<PopulatedForm>(); But in the face of generated code, this gets harder. In winforms a second file composing the rest of the partial class is generated. This file references other components, such as custom controls, and uses no-args constructors to create such controls: // generated file: PopulatedForm.Designer.cs public partial class PopulatedForm { private void InitializeComponent() { this.customComboBox = new UserCreatedComboBox(); // customComboBox has an IComboDataService dependency } } Since this is generated code, I can't pass in the dependencies and there's no easy way to have my IoC container automatically inject all the dependencies. One solution is to pass in the dependencies of each child component to PopulatedForm even though it may not need them directly, such as with the IComboDataService required by the UserCreatedComboBox. I then have the responsibility to make sure that the dependencies are provided through various properties or setter methods. Then, my PopulatedForm constructor might look as follows: public PopulatedForm(IDataService service, IComboDataService comboDataService) { this.service = service; InitializeComponent(); this.customComboBox.ComboDataService = comboDataService; } Another possible solution is to have the no-args constructor to do the necessary resolution: public class UserCreatedComboBox { private IComboDataService comboDataService; public UserCreatedComboBox() { if (!DesignMode && IoC.Instance != null) { comboDataService = Ioc.Instance.Resolve<IComboDataService>(); } } } Neither solution is particularly good. What patterns and alternatives are available to more capably handle dependency-injection in the face of generated code? I'd love to see both general solutions, such as patterns, and ones specific to C#, Winforms, and Autofac.

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• Besides DI, what benefits can I get from an IoC container?

  - by MOZILLA

  IoC Frameworks just make DI much easier, but it's not only DI that they do, they provide a host of other benefits over and above DI. I saw this comment in one of the answers to a question about DI and IoC. Can someone explain this in some more details? What are other benefits of IoC?

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• Spring 3 DI using generic DAO interface

  - by Peders

  I'm trying to use @Autowired annotation with my generic Dao interface like this: public interface DaoContainer<E extends DomainObject> { public int numberOfItems(); // Other methods omitted for brevity } I use this interface in my Controller in following fashion: @Configurable public class HelloWorld { @Autowired private DaoContainer<Notification> notificationContainer; @Autowired private DaoContainer<User> userContainer; // Implementation omitted for brevity } I've configured my application context with following configuration <context:spring-configured /> <context:component-scan base-package="com.organization.sample"> <context:exclude-filter expression="org.springframework.stereotype.Controller" type="annotation" /> </context:component-scan> <tx:annotation-driven /> This works only partially, since Spring creates and injects only one instance of my DaoContainer, namely DaoContainer. In other words, if I ask userContainer.numberOfItems(); I get the number of notificationContainer.numberOfItems() I've tried to use strongly typed interfaces to mark the correct implementation like this: public interface NotificationContainer extends DaoContainer<Notification> { } public interface UserContainer extends DaoContainer<User> { } And then used these interfaces like this: @Configurable public class HelloWorld { @Autowired private NotificationContainer notificationContainer; @Autowired private UserContainer userContainer; // Implementation omitted... } Sadly this fails to BeanCreationException: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.organization.sample.dao.NotificationContainer com.organization.sample.HelloWorld.notificationContainer; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.organization.sample.NotificationContainer] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} Now, I'm a little confused how should I proceed or is using multiple Dao's even possible. Any help would be greatly appreciated :)

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• Winforms MVP with Castle Windsor - DI for subforms?

  - by Paul Kirby

  I'm building a winforms app utilizing passive-view MVP and Castle Windsor as an IoC container. I'm still a little new to dependency injection and MVP, so I'm looking for some clarity... I have a main form which contains a number of user controls, and also will bring up other dialogs (ex. Login, options, etc) as needed. My first question is...should I use constructor injection to get the presenters for these other views into the main view, or should I go back to a Service Locator-type pattern? (which I've been told is a big nono!) Or something else? Second question...the user controls need to communicate back to the main form when they are "completed" (definition of that state varies based on the control). Is there a standard way of hooking these up? I was thinking perhaps just wiring up events between the main presenter and the child presenters, but I'm not sure if this is proper thinking. I'd appreciate any help, it seems that the combination of MVP and IoC in winforms isn't exactly well-documented.

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• C#, DI, IOC using Castle Windsor

  - by humblecoder

  Hi! Am working on a design of a project. I would like to move the implementation away hence to decouple am using interfaces. interface IFoo { void Bar(); void Baz(); } The assemblies which implemented the above interface would be drop in some predefined location say "C:\Plugins" for eg: project: A class A : IFoo { } when compiled produces A.dll project: B class A : IFoo { } when compiled produced B.dll Now I would like to provide a feature in my application to enable end use to configure the assembly to be loaded in the database.say C:\Plugins\A.dll or C:\Plugins\B.dll How it can be achieved using Castle Windsor. container.AddComponent("identifier",load assembly from specified location as configured in DB); I would like to do something like this: IFoo foo =container.Resolve("identifier"); foo.Bar(); //invoke method. Any hint would be highly appreciated. Thanks, Hamed.

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• With Google Website Optimizer's multivariate testing, can I vary multiple css classes on a single di

  - by brahn

  I would like to use Google Website Optimizer (GWO)'s multivariate tests to test some different versions of a web page. I can change from version to version just by varying some class tags on a div, i.e. the different versions are of this form: <div id="testing" class="foo1 bar1">content</div> <div id="testing" class="foo1 bar2">content</div> <div id="testing" class="foo2 bar1">content</div> <div id="testing" class="foo2 bar2">content</div> In the ideal, I would be able to use GWO section code in place of each class, and google would just swap in the appropriate tags (foo1 or foo2, bar1 or bar2). However, naively doing this results in horribly malformed code because I would be trying to put <script> tags inside the div's class attribute: <div id="testing" class=" <script>utmx_section("foo-class")</script>foo1</noscript> <script>utmx_section("bar-class")</script>bar1</noscript> "> content </div> And indeed, the browser chokes all over it. My current best approach is just to use a different div for each variable in the test, as follows: <script>utmx_section("foo-class-div")</script> <div class="foo1"> </noscript> <script>utmx_section("bar-class-div")</script> <div class="bar1"> </noscript> content </div> </div> So testing multiple variables requires layer of div-nesting per variable, and it all seems rather awkward. Is there a better approach that I could use in which I just vary the classes on a single div?

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• Ninject: Shared DI/IoC container

  - by joblot

  Hi I want to share the container across various layers in my application. I started creating a static class which initialises the container and register types in the container. public class GeneralDIModule : NinjectModule { public override void Load() { Bind().To().InSingletonScope(); } } public abstract class IoC { private static IKernel _container; public static void Initialize() { _container = new StandardKernel(new GeneralDIModule(), new ViewModelDIModule()); } public static T Get<T>() { return _container.Get<T>(); } } I noticed there is a Resolve method as well. What is the difference between Resolve and Get? In my unit tests I don’t always want every registered type in my container. Is there a way of initializing an empty container and then register types I need. I’ll be mocking types as well in unit test so I’ll have to register them as well. There is an Inject method, but it says lifecycle of instance is not managed? Could someone please set me in right way? How can I register, unregister objects and reset the container. Thanks

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• Accessing the DI container from anywhere

  - by ChrisR

  I've implemented the Symfony2 Dependency Injection container in my Zend Framework project and it works fine in the MVC layer of my application. I've initialized the DIC in my bootstrap and can access it anywhere by calling: Zend_Controller_Front::getInstance()->getParam('bootstrap')->getDic() The problem is that there are some parts of my application that do not utilize the Zend Framework application/MVC layer. My CLI tools for example. I could perfectly initialize a new DIC there but that would just be some copy paste work from the Bootstrap file which is asking for trouble down the road (DRY principles, etc) Is it a better solution to make my DIC available in the Zend_Registry or as a singleton called by a static method DIC::getInstance() for example? I know Registry and singletons are considered bad things but the DIC is such a high level part of the application that I will probably never run into the problems that make it a bad thing. Is this a good solution or are there better ways of accomplishing a globally accessible DIC?

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• Is there a pattern for initializing objects created wth a DI container

  - by Igor Zevaka

  I am trying to get Unity to manage the creation of my objects and I want to have some initialization parameters that are not known until run-time: At the moment the only way I could think of the way to do it is to have an Init method on the interface. interface IMyIntf { void Initialize(string runTimeParam); string RunTimeParam { get; } } Then to use it (in Unity) I would do this: var IMyIntf = unityContainer.Resolve<IMyIntf>(); IMyIntf.Initialize("somevalue"); In this scenario runTimeParam param is determined at run-time based on user input. The trivial case here simply returns the value of runTimeParam but in reality the parameter will be something like file name and initialize method will do something with the file. This creates a number of issues, namely that the Initialize method is available on the interface and can be called multiple times. Setting a flag in the implementation and throwing exception on repeated call to Initialize seems way clunky. At the point where I resolve my interface I don't want to know anything about the implementation of IMyIntf. What I do want, though, is the knowledge that this interface needs certain one time initialization parameters. Is there a way to somehow annotate(attributes?) the interface with this information and pass those to framework when the object is created? Edit: Described the interface a bit more.

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• IoC and DI framework for .Net applications

  - by Lijo

  Hi Can you please explain how the following three are different in their intent? 1) Policy Injection Application Block 2) Structure Map IoC Managed 3) Managed Extensibility Framework In terms of the common tasks they do, which is simpler/aligned with generics and C# 3.0 ? Thanks Lijo

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• DI with disposable objects

  - by sunnychaganty

  Suppose my repository class looks like this: class myRepository : IDisposable{ private DataContext _context; public myRepository(DataContext context){ _context = context; } public void Dispose(){ // to do: implement dispose of DataContext } } now, I am using Unity to control the lifetime of my repository & the data context & configured the lifetimes as: DataContext - singleton myRepository - create a new instance each time Does this mean that I should not be implementing the IDisposable on the repository to clean up the DataContext? Any guidance on such items?

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• DI: Injecting ActionFilterAttribute implementation (ASP.NET MVC)

  - by Sosh

  I was wondering if it is possible to inject a particular ActionFilterAttribute implementation using a IoC container. For example, imagine you create a TransactionAttribute class [Transaction] You use this to decorate action which should be wrapped in a transaction in the persistence layer. But implementation details of the attribute will be tied to the persistence tech you are using, but strictly speaking, your controller should not know about this, and you might want to swap this out. What I would like to do, is define some kind of TransactionAttribute interface, and then have my IoC inject the correct implantation. So on my actions I only need specify: [Transaction] public ActionResult SomeAction() { .... } ...and the IoC will inject the correct implementation depending on config (eg. something like NHibernateTransactionAttribute, or SomeOtherORMTransactionAttribute). Is this possible? Has anyone done it?

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