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• Checking preconditions or not

  - by Robert Dailey

  I've been wanting to find a solid answer to the question of whether or not to have runtime checks to validate input for the purposes of ensuring a client has stuck to their end of the agreement in design by contract. For example, consider a simple class constructor: class Foo { public: Foo( BarHandle bar ) { FooHandle handle = GetFooHandle( bar ); if( handle == NULL ) { throw std::exception( "invalid FooHandle" ); } } }; I would argue in this case that a user should not attempt to construct a Foo without a valid BarHandle. It doesn't seem right to verify that bar is valid inside of Foo's constructor. If I simply document that Foo's constructor requires a valid BarHandle, isn't that enough? Is this a proper way to enforce my precondition in design by contract? So far, everything I've read has mixed opinions on this. It seems like 50% of people would say to verify that bar is valid, the other 50% would say that I shouldn't do it, for example consider a case where the user verifies their BarHandle is correct, but a second (and unnecessary) check is also being done inside of Foo's constructor.

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• F# Objects &ndash; Part 3 &ndash; it&rsquo;s time to overload&hellip;

  - by MarkPearl

  Okay, some basic examples of overloading in F# Overloading Constructors Assume you have a F# object called person… type Person (firstname : string, lastname : string) = member v.Fullname = firstname + " " + lastname   This only has one constructor. To add additional constructors to the object by explicitly declaring them using the method member new. type Person (firstname : string, lastname : string) = new () = Person("Unknown", "Unknown") member v.Fullname = firstname + " " + lastname   In the code above I added another constructor to the Person object that takes no parameters and then refers to the primary constructor. Using the same technique in the code below I have created another constructor that accepts only the firstname as a parameter to create an object. type Person (firstname : string, lastname : string) = new () = Person("Unknown", "Unknown") new (firstname : string) = Person(firstname, "Unknown") member v.Fullname = firstname + " " + lastname   Overloading Operators So, you can overload operators of objects in F# as well… let’s look at example code… type Person(name : string) = member v.name = name static member (+) (person1 : Person , person2 : Person) = Person(person1.name + " " + person2.name)   In the code above we have overloaded the “+” operator. Whenever we add to Person objects together, it will now create a new object with the combined names…

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• How-to configure Spring Social via XML

  - by Matthias Steiner

  I spend a few hours trying to get Twitter integration to work with Spring Social using the XML configuration approach. All the examples I could find on the web (and on stackoverflow) always use the @Config approach as shown in the samples For whatever reason the bean definition to get an instance to the twitter API throws an AOP exception: Caused by: java.lang.IllegalStateException: Cannot create scoped proxy for bean 'scopedTarget.twitter': Target type could not be determined at the time of proxy creation. Here's the complete config file I have: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jaxrs="http://cxf.apache.org/jaxrs" xmlns:context="http://www.springframework.org/schema/context" xmlns:util="http://www.springframework.org/schema/util" xmlns:cxf="http://cxf.apache.org/core" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:jee="http://www.springframework.org/schema/jee" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:jdbc="http://www.springframework.org/schema/jdbc" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/jaxrs.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd http://cxf.apache.org/core http://cxf.apache.org/schemas/core.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.1.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd"> <import resource="classpath:META-INF/cxf/cxf.xml" /> <import resource="classpath:META-INF/cxf/cxf-servlet.xml" /> <jee:jndi-lookup id="dataSource" jndi-name="java:comp/env/jdbc/DefaultDB" /> <!-- initialize DB required to store user auth tokens --> <jdbc:initialize-database data-source="dataSource" ignore-failures="ALL"> <jdbc:script location="classpath:/org/springframework/social/connect/jdbc/JdbcUsersConnectionRepository.sql"/> </jdbc:initialize-database> <bean id="connectionFactoryLocator" class="org.springframework.social.connect.support.ConnectionFactoryRegistry"> <property name="connectionFactories"> <list> <ref bean="twitterConnectFactory" /> </list> </property> </bean> <bean id="twitterConnectFactory" class="org.springframework.social.twitter.connect.TwitterConnectionFactory"> <constructor-arg value="xyz" /> <constructor-arg value="xzy" /> </bean> <bean id="usersConnectionRepository" class="org.springframework.social.connect.jdbc.JdbcUsersConnectionRepository"> <constructor-arg ref="dataSource" /> <constructor-arg ref="connectionFactoryLocator" /> <constructor-arg ref="textEncryptor" /> </bean> <bean id="connectionRepository" factory-method="createConnectionRepository" factory-bean="usersConnectionRepository" scope="request"> <constructor-arg value="#{request.userPrincipal.name}" /> <aop:scoped-proxy proxy-target-class="false" /> </bean> <bean id="twitter" factory-method="?ndPrimaryConnection" factory-bean="connectionRepository" scope="request" depends-on="connectionRepository"> <constructor-arg value="org.springframework.social.twitter.api.Twitter" /> <aop:scoped-proxy proxy-target-class="false" /> </bean> <bean id="textEncryptor" class="org.springframework.security.crypto.encrypt.Encryptors" factory-method="noOpText" /> <bean id="connectController" class="org.springframework.social.connect.web.ConnectController"> <constructor-arg ref="connectionFactoryLocator"/> <constructor-arg ref="connectionRepository"/> <property name="applicationUrl" value="https://socialscn.int.netweaver.ondemand.com/socialspringdemo" /> </bean> <bean id="signInAdapter" class="com.sap.netweaver.cloud.demo.social.SimpleSignInAdapter" /> </beans> What puzzles me is that the connectionRepositoryinstantiation works perfectly fine (I commented-out the twitter bean and tested the code!) ?!? It uses the same features: request scope and interface AOP proxy and works, but the twitter bean instantiation fails ?!? The spring social config code looks as follows (I can not see any differences, can you?): @Configuration public class SocialConfig { @Inject private Environment environment; @Inject private DataSource dataSource; @Bean @Scope(value="singleton", proxyMode=ScopedProxyMode.INTERFACES) public ConnectionFactoryLocator connectionFactoryLocator() { ConnectionFactoryRegistry registry = new ConnectionFactoryRegistry(); registry.addConnectionFactory(new TwitterConnectionFactory(environment.getProperty("twitter.consumerKey"), environment.getProperty("twitter.consumerSecret"))); return registry; } @Bean @Scope(value="singleton", proxyMode=ScopedProxyMode.INTERFACES) public UsersConnectionRepository usersConnectionRepository() { return new JdbcUsersConnectionRepository(dataSource, connectionFactoryLocator(), Encryptors.noOpText()); } @Bean @Scope(value="request", proxyMode=ScopedProxyMode.INTERFACES) public ConnectionRepository connectionRepository() { Authentication authentication = SecurityContextHolder.getContext().getAuthentication(); if (authentication == null) { throw new IllegalStateException("Unable to get a ConnectionRepository: no user signed in"); } return usersConnectionRepository().createConnectionRepository(authentication.getName()); } @Bean @Scope(value="request", proxyMode=ScopedProxyMode.INTERFACES) public Twitter twitter() { Connection<Twitter> twitter = connectionRepository().findPrimaryConnection(Twitter.class); return twitter != null ? twitter.getApi() : new TwitterTemplate(); } @Bean public ConnectController connectController() { ConnectController connectController = new ConnectController(connectionFactoryLocator(), connectionRepository()); connectController.addInterceptor(new PostToWallAfterConnectInterceptor()); connectController.addInterceptor(new TweetAfterConnectInterceptor()); return connectController; } @Bean public ProviderSignInController providerSignInController(RequestCache requestCache) { return new ProviderSignInController(connectionFactoryLocator(), usersConnectionRepository(), new SimpleSignInAdapter(requestCache)); } } Any help/pointers would be appreciated!!! Cheers, Matthias

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• Using Unity – Part 5

  - by nmarun

  In the previous article of the series, I talked about constructor and property (setter) injection. I wanted to write about how to work with arrays and generics in Unity in this blog, after seeing how lengthy this one got, I’ve decided to write about generics in the next one. This one will only concentrate on arrays. My Product4 class has the following definition: 1: public interface IProduct 2: { 3: string WriteProductDetails(); 4: } 5:  6: public class Product4 : IProduct 7: { 8: public string Name { get; set; } 9: public ILogger[] Loggers { get; set; } 10:  11: public Product4(string productName, ILogger[] loggers) 12: { 13: Name = productName; 14: Loggers = loggers; 15: } 16:  17: public string WriteProductDetails() 18: { 19: StringBuilder productDetails = new StringBuilder(); 20: productDetails.AppendFormat("{0}<br/>", Name); 21: for (int i = 0; i < Loggers.Count(); i++) 22: { 23: productDetails.AppendFormat("{0}<br/>", Loggers[i].WriteLog()); 24: } 25: 26: return productDetails.ToString(); 27: } 28: } The key parts are line 4 where we declare an array of ILogger and line 5 where-in the constructor passes an instance of an array of ILogger objects. I’ve created another class – FakeLogger: 1: public class FakeLogger : ILogger 2: { 3: public string WriteLog() 4: { 5: return string.Format("Type: {0}", GetType()); 6: } 7: } It’s implementation is the same as what we had for the FileLogger class. Coming to the web.config file, first add the following aliases. The alias for FakeLogger should make sense right away. ILoggerArray defines an array of ILogger objects. I’ll tell why we need an alias for System.String data type. 1: <typeAlias alias="string" type="System.String, mscorlib" /> 2: <typeAlias alias="ILoggerArray" type="ProductModel.ILogger[], ProductModel" /> 3: <typeAlias alias="FakeLogger" type="ProductModel.FakeLogger, ProductModel"/> Next is to create mappings for the FileLogger and FakeLogger classes: 1: <type type="ILogger" mapTo="FileLogger" name="logger1"> 2: <lifetime type="singleton" /> 3: </type> 4: <type type="ILogger" mapTo="FakeLogger" name="logger2"> 5: <lifetime type="singleton" /> 6: </type> Finally, for the real deal: 1: <type type="IProduct" mapTo="Product4" name="ArrayProduct"> 2: <typeConfig extensionType="Microsoft.Practices.Unity.Configuration.TypeInjectionElement,Microsoft.Practices.Unity.Configuration, Version=1.2.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"> 3: <constructor> 4: <param name="productName" parameterType="string" > 5: <value value="Product name from config file" type="string"/> 6: </param> 7: <param name="loggers" parameterType="ILoggerArray"> 8: <array> 9: <dependency name="logger2" /> 10: <dependency name="logger1" /> 11: </array> 12: </param> 13: </constructor> 14: </typeConfig> 15: </type> Here’s where I’m saying, that if a type of IProduct is requested to be resolved, map it to type Product4. Furthermore, the Product4 has two constructor parameters – a string and an array of type ILogger. You might have observed the first parameter of the constructor is named ‘productName’ and that matches the value in the name attribute of the param element. The parameterType of ‘string’ maps to ‘System.String, mscorlib’ and is defined in the type alias above. The set up is similar for the second constructor parameter. The name matches the name of the parameter (loggers) and is of type ILoggerArray, which maps to an array of ILogger objects. We’ve also decided to add two elements to this array when unity resolves it – an instance of FileLogger and one of FakeLogger. The click event of the button does the following: 1: //unityContainer.RegisterType<IProduct, Product4>(); 2: //IProduct product4 = unityContainer.Resolve<IProduct>(); 3: IProduct product4 = unityContainer.Resolve<IProduct>("ArrayConstructor"); 4: productDetailsLabel.Text = product4.WriteProductDetails(); It’s worth mentioning here about the change in the format of resolving the IProduct to create an instance of Product4. You cannot use the regular way (the commented lines) to get an instance of Product4. The reason is due to the behavior of Unity which Alex Ermakov has brilliantly explained here. The corresponding output of the action is: You have a couple of options when it comes to adding dependency elements in the array node. You can: - leave it empty (no dependency elements declared): This will only create an empty array of loggers. This way you can check for non-null condition, in your mock classes. - add multiple dependency elements with the same name 1: <param name="loggers" parameterType="ILoggerArray"> 2: <array> 3: <dependency name="logger2" /> 4: <dependency name="logger2" /> 5: </array> 6: </param> With this you’ll see two instances of FakeLogger in the output. This article shows how Unity allows you to instantiate objects with arrays. Find the code here.

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• ASP.NET exception gives irrelevant stack trace on YSOD, very challenging!

  - by pootow

  Here is the YSOD: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [SqlException (0x80131904): Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.] System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +428 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +65 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +117 System.Data.SqlClient.SqlConnection.Open() +122 ECommerce.PMethod.Sql.SqlConns.Open() +78 ECommerce.PMethod.Sql.SqlConns..ctor() +120 ECommerce.login.DatasInfo.Proc.UserCenter.IsLogin(String UserGUID, Int32 UserID) +49 ECommerce.login.Rules.Users.UserLogin.isLogin() +44 Config.isUserLogined() +5 Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14 System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35 System.Web.UI.Control.OnLoad(EventArgs e) +99 System.Web.UI.Control.LoadRecursive() +50 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627 [TypeInitializationException: The type initializer for 'ECommerce.ERP.DAL.DBConn' threw an exception.] ECommerce.ERP.DAL.DBConn.get_ConnString() +0 [ObjectDefinitionStoreException: Factory method 'System.String get_ConnString()' threw an Exception.] Spring.Objects.Factory.Support.SimpleInstantiationStrategy.Instantiate(RootObjectDefinition definition, String name, IObjectFactory factory, MethodInfo factoryMethod, Object[] arguments) +257 Spring.Objects.Factory.Support.ConstructorResolver.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +624 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +60 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +56 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +436 [ObjectCreationException: Error thrown by a dependency of object 'styleService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 56' : Initialization of object failed : Factory method 'System.String get_ConnString()' threw an Exception. while resolving 'constructor argument with name promotionservice' to 'promotionService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 31' while resolving 'constructor argument with name domainservice' to 'promotionDomainService' defined in 'assembly [ECommerce.Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Domain.AppContext.xml] line 20' while resolving 'constructor argument with name promotionrepos' to 'promotionRepos' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34' while resolving 'constructor argument with name connstr' to 'ECommerce.ERP.DAL.DBConn#389F399' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34'] Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveReference(IObjectDefinition definition, String name, String argumentName, RuntimeObjectReference reference) +394 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolvePropertyValue(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +312 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveValueIfNecessary(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +17 Spring.Objects.Factory.Support.ConstructorResolver.ResolveConstructorArguments(String objectName, RootObjectDefinition definition, ObjectWrapper wrapper, ConstructorArgumentValues cargs, ConstructorArgumentValues resolvedValues) +993 Spring.Objects.Factory.Support.ConstructorResolver.AutowireConstructor(String objectName, RootObjectDefinition rod, ConstructorInfo[] chosenCtors, Object[] explicitArgs) +171 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.AutowireConstructor(String name, RootObjectDefinition definition, ConstructorInfo[] ctors, Object[] explicitArgs) +65 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +161 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +636 Spring.Objects.Factory.Support.AbstractObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +174 Spring.Objects.Factory.Support.WebObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +150 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObjectInternal(String name, Type requiredType, Object[] arguments, Boolean suppressConfigure) +990 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObject(String name) +10 Spring.Context.Support.AbstractApplicationContext.GetObject(String name) +20 ECommerce.Common.ServiceLocator.GetService() +334 ECommerce.Mvc.Controllers.StylesController..ctor() +72 [TargetInvocationException: Exception has been thrown by the target of an invocation.] System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) +86 System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) +230 System.Activator.CreateInstance(Type type, Boolean nonPublic) +67 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +80 [InvalidOperationException: An error occurred when trying to create a controller of type 'ECommerce.Mvc.Controllers.StylesController'. Make sure that the controller has a parameterless public constructor.] System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +190 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +68 System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +118 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +46 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +63 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +13 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8677954 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082 Question is: the first stack trace is irrelevant to others, what happened? Any ideas? Let me make this more clear: a MVC page uses the spring part trying to load a lazy-init service which constructor wants a connection string through a static property like this: <object id="promotionRepos" type="ECommerce.Data.AdoNet.Promotions.PromotionRepos, ECommerce.Data.AdoNet" lazy-init="true"> <constructor-arg name="provider"> <null /> </constructor-arg> <constructor-arg name="connStr"> <object type="ECommerce.ERP.DAL.DBConn, ECommerce.ERP.DAL" factory-method="get_ConnString" /> </constructor-arg> <property name="RefreshInterval" value="00:00:10" /> </object> the timeout part is some what irrelevent to all others. see this in the first exception: Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 it's another page at all. And also, ECommerce.PMethod.Sql.SqlConns.Open() uses its own connection string, not the one loaded by spring, it's different module from diffrent team. And I am sure the connection string is correct. And, this ysod cames up randomly. Sometimes nothing is wrong, and sometimes, it appears. I thought there could be something wrong with my database or the network/firewall, I will check it later, but now I want understand this tricky stack trace.

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• MVVM for Dummies

  - by Martin Hinshelwood

  I think that I have found one of the best articles on MVVM that I have ever read: http://jmorrill.hjtcentral.com/Home/tabid/428/EntryId/432/MVVM-for-Tarded-Folks-Like-Me-or-MVVM-and-What-it-Means-to-Me.aspx This article sums up what is in MVVM and what is outside of MVVM. Note, when I and most other people say MVVM, they really mean MVVM, Commanding, Dependency Injection + any other Patterns you need to create your application. In WPF a lot of use is made of the Decorator and Behaviour pattern as well. The goal of all of this is to have pure separation of concerns. This is what every code behind file of every Control / Window / Page  should look like if you are engineering your WPF and Silverlight correctly: C# – Ideal public partial class IdealView : UserControl { public IdealView() { InitializeComponent(); } } Figure: This is the ideal code behind for a Control / Window / Page when using MVVM. C# – Compromise, but works public partial class IdealView : UserControl { public IdealView() { InitializeComponent(); this.DataContext = new IdealViewModel(); } } Figure: This is a compromise, but the best you can do without Dependency Injection VB.NET – Ideal Partial Public Class ServerExplorerConnectView End Class Figure: This is the ideal code behind for a Control / Window / Page when using MVVM. VB.NET – Compromise, but works Partial Public Class ServerExplorerConnectView Private Sub ServerExplorerConnectView_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded Me.DataContext = New ServerExplorerConnectViewModel End Sub End Class Figure: This is a compromise, but the best you can do without Dependency Injection Technorati Tags: MVVM,.NET,WPF,Silverlight

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• Unity – Part 5: Injecting Values

  - by Ricardo Peres

  Introduction This is the fifth post on Unity. You can find the introductory post here, the second post, on dependency injection here, a third one on Aspect Oriented Programming (AOP) here and the latest so far, on writing custom extensions, here. This time we will talk about injecting simple values. An Inversion of Control (IoC) / Dependency Injector (DI) container like Unity can be used for things other than injecting complex class dependencies. It can also be used for setting property values or method/constructor parameters whenever a class is built. The main difference is that these values do not have a lifetime manager associated with them and do not come from the regular IoC registration store. Unlike, for instance, MEF, Unity won’t let you register as a dependency a string or an integer, so you have to take a different approach, which I will describe in this post. Scenario Let’s imagine we have a base interface that describes a logger – the same as in previous examples: 1: public interface ILogger 2: { 3: void Log(String message); 4: } And a concrete implementation that writes to a file: 1: public class FileLogger : ILogger 2: { 3: public String Filename 4: { 5: get; 6: set; 7: } 8:  9: #region ILogger Members 10:  11: public void Log(String message) 12: { 13: using (Stream file = File.OpenWrite(this.Filename)) 14: { 15: Byte[] data = Encoding.Default.GetBytes(message); 16: 17: file.Write(data, 0, data.Length); 18: } 19: } 20:  21: #endregion 22: } And let’s say we want the Filename property to come from the application settings (appSettings) section on the Web/App.config file. As usual with Unity, there is an extensibility point that allows us to automatically do this, both with code configuration or statically on the configuration file. Extending Injection We start by implementing a class that will retrieve a value from the appSettings by inheriting from ValueElement: 1: sealed class AppSettingsParameterValueElement : ValueElement, IDependencyResolverPolicy 2: { 3: #region Private methods 4: private Object CreateInstance(Type parameterType) 5: { 6: Object configurationValue = ConfigurationManager.AppSettings[this.AppSettingsKey]; 7:  8: if (parameterType != typeof(String)) 9: { 10: TypeConverter typeConverter = this.GetTypeConverter(parameterType); 11:  12: configurationValue = typeConverter.ConvertFromInvariantString(configurationValue as String); 13: } 14:  15: return (configurationValue); 16: } 17: #endregion 18:  19: #region Private methods 20: private TypeConverter GetTypeConverter(Type parameterType) 21: { 22: if (String.IsNullOrEmpty(this.TypeConverterTypeName) == false) 23: { 24: return (Activator.CreateInstance(TypeResolver.ResolveType(this.TypeConverterTypeName)) as TypeConverter); 25: } 26: else 27: { 28: return (TypeDescriptor.GetConverter(parameterType)); 29: } 30: } 31: #endregion 32:  33: #region Public override methods 34: public override InjectionParameterValue GetInjectionParameterValue(IUnityContainer container, Type parameterType) 35: { 36: Object value = this.CreateInstance(parameterType); 37: return (new InjectionParameter(parameterType, value)); 38: } 39: #endregion 40:  41: #region IDependencyResolverPolicy Members 42:  43: public Object Resolve(IBuilderContext context) 44: { 45: Type parameterType = null; 46:  47: if (context.CurrentOperation is ResolvingPropertyValueOperation) 48: { 49: ResolvingPropertyValueOperation op = (context.CurrentOperation as ResolvingPropertyValueOperation); 50: PropertyInfo prop = op.TypeBeingConstructed.GetProperty(op.PropertyName); 51: parameterType = prop.PropertyType; 52: } 53: else if (context.CurrentOperation is ConstructorArgumentResolveOperation) 54: { 55: ConstructorArgumentResolveOperation op = (context.CurrentOperation as ConstructorArgumentResolveOperation); 56: String args = op.ConstructorSignature.Split('(')[1].Split(')')[0]; 57: Type[] types = args.Split(',').Select(a => Type.GetType(a.Split(' ')[0])).ToArray(); 58: ConstructorInfo ctor = op.TypeBeingConstructed.GetConstructor(types); 59: parameterType = ctor.GetParameters().Where(p => p.Name == op.ParameterName).Single().ParameterType; 60: } 61: else if (context.CurrentOperation is MethodArgumentResolveOperation) 62: { 63: MethodArgumentResolveOperation op = (context.CurrentOperation as MethodArgumentResolveOperation); 64: String methodName = op.MethodSignature.Split('(')[0].Split(' ')[1]; 65: String args = op.MethodSignature.Split('(')[1].Split(')')[0]; 66: Type[] types = args.Split(',').Select(a => Type.GetType(a.Split(' ')[0])).ToArray(); 67: MethodInfo method = op.TypeBeingConstructed.GetMethod(methodName, types); 68: parameterType = method.GetParameters().Where(p => p.Name == op.ParameterName).Single().ParameterType; 69: } 70:  71: return (this.CreateInstance(parameterType)); 72: } 73:  74: #endregion 75:  76: #region Public properties 77: [ConfigurationProperty("appSettingsKey", IsRequired = true)] 78: public String AppSettingsKey 79: { 80: get 81: { 82: return ((String)base["appSettingsKey"]); 83: } 84:  85: set 86: { 87: base["appSettingsKey"] = value; 88: } 89: } 90: #endregion 91: } As you can see from the implementation of the IDependencyResolverPolicy.Resolve method, this will work in three different scenarios: When it is applied to a property; When it is applied to a constructor parameter; When it is applied to an initialization method. The implementation will even try to convert the value to its declared destination, for example, if the destination property is an Int32, it will try to convert the appSettings stored string to an Int32. Injection By Configuration If we want to configure injection by configuration, we need to implement a custom section extension by inheriting from SectionExtension, and registering our custom element with the name “appSettings”: 1: sealed class AppSettingsParameterInjectionElementExtension : SectionExtension 2: { 3: public override void AddExtensions(SectionExtensionContext context) 4: { 5: context.AddElement<AppSettingsParameterValueElement>("appSettings"); 6: } 7: } And on the configuration file, for setting a property, we use it like this: 1: <appSettings> 2: <add key="LoggerFilename" value="Log.txt"/> 3: </appSettings> 4: <unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> 5: <container> 6: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.ConsoleLogger, MyAssembly"/> 7: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.FileLogger, MyAssembly" name="File"> 8: <lifetime type="singleton"/> 9: <property name="Filename"> 10: <appSettings appSettingsKey="LoggerFilename"/> 11: </property> 12: </register> 13: </container> 14: </unity> If we would like to inject the value as a constructor parameter, it would be instead: 1: <unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> 2: <sectionExtension type="MyNamespace.AppSettingsParameterInjectionElementExtension, MyAssembly" /> 3: <container> 4: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.ConsoleLogger, MyAssembly"/> 5: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.FileLogger, MyAssembly" name="File"> 6: <lifetime type="singleton"/> 7: <constructor> 8: <param name="filename" type="System.String"> 9: <appSettings appSettingsKey="LoggerFilename"/> 10: </param> 11: </constructor> 12: </register> 13: </container> 14: </unity> Notice the appSettings section, where we add a LoggerFilename entry, which is the same as the one referred by our AppSettingsParameterInjectionElementExtension extension. For more advanced behavior, you can add a TypeConverterName attribute to the appSettings declaration, where you can pass an assembly qualified name of a class that inherits from TypeConverter. This class will be responsible for converting the appSettings value to a destination type. Injection By Attribute If we would like to use attributes instead, we need to create a custom attribute by inheriting from DependencyResolutionAttribute: 1: [Serializable] 2: [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Property, AllowMultiple = false, Inherited = true)] 3: public sealed class AppSettingsDependencyResolutionAttribute : DependencyResolutionAttribute 4: { 5: public AppSettingsDependencyResolutionAttribute(String appSettingsKey) 6: { 7: this.AppSettingsKey = appSettingsKey; 8: } 9:  10: public String TypeConverterTypeName 11: { 12: get; 13: set; 14: } 15:  16: public String AppSettingsKey 17: { 18: get; 19: private set; 20: } 21:  22: public override IDependencyResolverPolicy CreateResolver(Type typeToResolve) 23: { 24: return (new AppSettingsParameterValueElement() { AppSettingsKey = this.AppSettingsKey, TypeConverterTypeName = this.TypeConverterTypeName }); 25: } 26: } As for file configuration, there is a mandatory property for setting the appSettings key and an optional TypeConverterName  for setting the name of a TypeConverter. Both the custom attribute and the custom section return an instance of the injector AppSettingsParameterValueElement that we implemented in the first place. Now, the attribute needs to be placed before the injected class’ Filename property: 1: public class FileLogger : ILogger 2: { 3: [AppSettingsDependencyResolution("LoggerFilename")] 4: public String Filename 5: { 6: get; 7: set; 8: } 9:  10: #region ILogger Members 11:  12: public void Log(String message) 13: { 14: using (Stream file = File.OpenWrite(this.Filename)) 15: { 16: Byte[] data = Encoding.Default.GetBytes(message); 17: 18: file.Write(data, 0, data.Length); 19: } 20: } 21:  22: #endregion 23: } Or, if we wanted to use constructor injection: 1: public class FileLogger : ILogger 2: { 3: public String Filename 4: { 5: get; 6: set; 7: } 8:  9: public FileLogger([AppSettingsDependencyResolution("LoggerFilename")] String filename) 10: { 11: this.Filename = filename; 12: } 13:  14: #region ILogger Members 15:  16: public void Log(String message) 17: { 18: using (Stream file = File.OpenWrite(this.Filename)) 19: { 20: Byte[] data = Encoding.Default.GetBytes(message); 21: 22: file.Write(data, 0, data.Length); 23: } 24: } 25:  26: #endregion 27: } Usage Just do: 1: ILogger logger = ServiceLocator.Current.GetInstance<ILogger>("File"); And off you go! A simple way do avoid hardcoded values in component registrations. Of course, this same concept can be applied to registry keys, environment values, XML attributes, etc, etc, just change the implementation of the AppSettingsParameterValueElement class. Next stop: custom lifetime managers.

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• Munq is for web, Unity is for Enterprise

  - by oazabir

  The Unity Application Block (Unity) is a lightweight extensible dependency injection container with support for constructor, property, and method call injection. It’s a great library for facilitating Inversion of Control and the recent version supports AOP as well. However, when it comes to performance, it’s CPU hungry. In fact it’s so CPU hungry that it makes it impossible to make it work at Internet Scale. I was investigating some CPU issue on a portal that gets around 3MM hits per day and I found unusually high CPU. Here’s why: I did some CPU profiling on my open source project Dropthings and found that the highest CPU is consumed by Unity’s Resolve<>(). There’s no funky use of Unity in the project. Straightforward Register<>() and Resolve<>(). But as you can see, Resolve<>() is consuming significantly high CPU even after the site is warm and has been running for a while. Then I tried Munq, which is a basic Dependency Injection Container. It has everything you will usually need in a regular project. It boasts to be the fastest DI out there. So, I converted all Unity code to Munq in Dropthings and did a CPU profile and Whala!   There’s no trace of any Munq calls anywhere. That proves Munq is a lot faster than Unity.

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• Yet Yet Another Way To Create An Object

  - by Ricardo Peres

  Yep, there's still another one: FormatterServices. This one allows one to create an object without running it's constructor... it is used by some of our good friends serializers. Stopwatch watch = new Stopwatch(); for (Int32 i = 0; i Beware, though: because the constructor isn't run (and remember that all fields that are initialized inline are also in fact initialized in the constructor), the object's state may be invalid. Enough object construction for now... SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

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• Please help me to improve Re-Sharper

  - by TATWORTH

  Re-Sharper is an excellent aid to producing good code in either C# or VB.NET. Recently through using Resharper and StyleCop, I have found three area where ReSharper needs to be improved. Please log into the YouTrack at http://youtrack.jetbrains.net and vote for the following: RSRP-268868 Improvement to removal of redundant else and invert if optimisations for enhanced stylecop compliance. When Resharper removes a redundant else, there needs to be a blank line added. Currently there is no provision to specify this. Please vote for this! RSRP-272286 Resharper Feature Request to move initialisation to static constructor Currently ReSharper offers moving initialisation of of non-static variable to a constructor. Why not offer the same for a static constructor?  Please vote for this! RSRP-272285 Expansion of Switch Statement by Resharper Currently ReSharper will fill an empty switch statement based upon an enumeration but will not add missing enumeration values to such a switch statement.   Can't code withoutCoding assistance, smart code editing and code completion for C# and VB.NET

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• Techniques for sharing a value among classes in a program

  - by Kenneth Cochran

  I'm using Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData) + "\MyProgram" As the path to store several files used by my program. I'd like to avoid pasting the same snippet of code all over the my applcation. I need to ensure that: The path cannot be accidentally changed once its been set The classes that need it have access to it. I've considered: Making it a singleton Using constructor dependency injection Using property dependency injection Using AOP to create the path where its needed. Each has pros and cons. The singleton is everyone's favorite whipping boy. I'm not opposed to using one but there are valid reasons to avoid it if possible. I'm already heavily using constructor injection through Castle Windsor. But this is a path string and Windsor doesn't handle system type dependencies very gracefully. I could always wrap it in a class but that seems like overkill for something as simple as a passing around a string value. In any case this route would add yet another constructor argument to each class where it is used. The problem I see with property injection in this case is that there is a large amount of indirection from the where the value is set to where it is needed. I would need a very long line of middlemen to reach all the places where its used. AOP looks promising and I'm planning on using AOP for logging anyway so this at least sounds like a simple solution. Is there any other options I haven't considered? Am I off base with my evaluation of the options I have considered?

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• New <%: %> Syntax for HTML Encoding Output in ASP.NET 4 (and ASP.NET MVC 2)

  - by ScottGu

  [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] This is the nineteenth in a series of blog posts I’m doing on the upcoming VS 2010 and .NET 4 release. Today’s post covers a small, but very useful, new syntax feature being introduced with ASP.NET 4 – which is the ability to automatically HTML encode output within code nuggets.  This helps protect your applications and sites against cross-site script injection (XSS) and HTML injection attacks, and enables you to do so using a nice concise syntax. HTML Encoding Cross-site script injection (XSS) and HTML encoding attacks are two of the most common security issues that plague web-sites and applications.  They occur when hackers find a way to inject client-side script or HTML markup into web-pages that are then viewed by other visitors to a site.  This can be used to both vandalize a site, as well as enable hackers to run client-script code that steals cookie data and/or exploits a user’s identity on a site to do bad things. One way to help mitigate against cross-site scripting attacks is to make sure that rendered output is HTML encoded within a page.  This helps ensures that any content that might have been input/modified by an end-user cannot be output back onto a page containing tags like <script> or <img> elements.  ASP.NET applications (especially those using ASP.NET MVC) often rely on using <%= %> code-nugget expressions to render output.  Developers today often use the Server.HtmlEncode() or HttpUtility.Encode() helper methods within these expressions to HTML encode the output before it is rendered.  This can be done using code like below: While this works fine, there are two downsides of it: It is a little verbose Developers often forget to call the HtmlEncode method New <%: %> Code Nugget Syntax With ASP.NET 4 we are introducing a new code expression syntax (<%:  %>) that renders output like <%= %> blocks do – but which also automatically HTML encodes it before doing so.  This eliminates the need to explicitly HTML encode content like we did in the example above.  Instead you can just write the more concise code below to accomplish the same thing: We chose the <%: %> syntax so that it would be easy to quickly replace existing instances of <%= %> code blocks.  It also enables you to easily search your code-base for <%= %> elements to find and verify any cases where you are not using HTML encoding within your application to ensure that you have the correct behavior. Avoiding Double Encoding While HTML encoding content is often a good best practice, there are times when the content you are outputting is meant to be HTML or is already encoded – in which case you don’t want to HTML encode it again.  ASP.NET 4 introduces a new IHtmlString interface (along with a concrete implementation: HtmlString) that you can implement on types to indicate that its value is already properly encoded (or otherwise examined) for displaying as HTML, and that therefore the value should not be HTML-encoded again.  The <%: %> code-nugget syntax checks for the presence of the IHtmlString interface and will not HTML encode the output of the code expression if its value implements this interface.  This allows developers to avoid having to decide on a per-case basis whether to use <%= %> or <%: %> code-nuggets.  Instead you can always use <%: %> code nuggets, and then have any properties or data-types that are already HTML encoded implement the IHtmlString interface. Using ASP.NET MVC HTML Helper Methods with <%: %> For a practical example of where this HTML encoding escape mechanism is useful, consider scenarios where you use HTML helper methods with ASP.NET MVC.  These helper methods typically return HTML.  For example: the Html.TextBox() helper method returns markup like <input type=”text”/>.  With ASP.NET MVC 2 these helper methods now by default return HtmlString types – which indicates that the returned string content is safe for rendering and should not be encoded by <%: %> nuggets.  This allows you to use these methods within both <%= %> code nugget blocks: As well as within <%: %> code nugget blocks: In both cases above the HTML content returned from the helper method will be rendered to the client as HTML – and the <%: %> code nugget will avoid double-encoding it. This enables you to default to always using <%: %> code nuggets instead of <%= %> code blocks within your applications.  If you want to be really hardcore you can even create a build rule that searches your application looking for <%= %> usages and flags any cases it finds as an error to enforce that HTML encoding always takes place. Scaffolding ASP.NET MVC 2 Views When you use VS 2010 (or the free Visual Web Developer 2010 Express) you’ll find that the views that are scaffolded using the “Add View” dialog now by default always use <%: %> blocks when outputting any content.  For example, below I’ve scaffolded a simple “Edit” view for an article object.  Note the three usages of <%: %> code nuggets for the label, textbox, and validation message (all output with HTML helper methods): Summary The new <%: %> syntax provides a concise way to automatically HTML encode content and then render it as output.  It allows you to make your code a little less verbose, and to easily check/verify that you are always HTML encoding content throughout your site.  This can help protect your applications against cross-site script injection (XSS) and HTML injection attacks.  Hope this helps, Scott

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• Creating Entity Framework objects with Unity for Unit of Work/Repository pattern

  - by TobyEvans

  Hi there, I'm trying to implement the Unit of Work/Repository pattern, as described here: http://blogs.msdn.com/adonet/archive/2009/06/16/using-repository-and-unit-of-work-patterns-with-entity-framework-4-0.aspx This requires each Repository to accept an IUnitOfWork implementation, eg an EF datacontext extended with a partial class to add an IUnitOfWork interface. I'm actually using .net 3.5, not 4.0. My basic Data Access constructor looks like this: public DataAccessLayer(IUnitOfWork unitOfWork, IRealtimeRepository realTimeRepository) { this.unitOfWork = unitOfWork; this.realTimeRepository = realTimeRepository; } So far, so good. What I'm trying to do is add Dependency Injection using the Unity Framework. Getting the EF data context to be created with Unity was an adventure, as it had trouble resolving the constructor - what I did in the end was to create another constructor in my partial class with a new overloaded constructor, and marked that with [InjectionConstructor] [InjectionConstructor] public communergyEntities(string connectionString, string containerName) :this() { (I know I need to pass the connection string to the base object, that can wait until once I've got all the objects initialising correctly) So, using this technique, I can happily resolve my entity framework object as an IUnitOfWork instance thus: using (IUnityContainer container = new UnityContainer()) { container.RegisterType<IUnitOfWork, communergyEntities>(); container.Configure<InjectedMembers>() .ConfigureInjectionFor<communergyEntities>( new InjectionConstructor("a", "b")) DataAccessLayer target = container.Resolve<DataAccessLayer>(); Great. What I need to do now is create the reference to the repository object for the DataAccessLayer - the DAL only needs to know the interface, so I'm guessing that I need to instantiate it as part of the Unity Resolve statement, passing it the appropriate IUnitOfWork interface. In the past, I would have just passed the Repository constructor the db connection string, and it would have gone away, created a local Entity Framework object and used that just for the lifetime of the Repository method. This is different, in that I create an Entity Framework instance as an IUnitOfWork implementation during the Unity Resolve statement, and it's that instance I need to pass into the constructor of the Repository - is that possible, and if so, how? I'm wondering if I could make the Repository a property and mark it as a Dependency, but that still wouldn't solve the problem of how to create the Repository with the IUnitOfWork object that the DAL is being Resolved with I'm not sure if I've understood this pattern correctly, and will happily take advice on the best way to implement it - Entity Framework is staying, but Unity can be swapped out if not the best approach. If I've got the whole thing upside down, please tell me thanks

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• How to send keypresses from qt application to libvlc

  - by anon

  I need to send keypresses from my application window to libvlc, how do i do that? I tried using varSetInteger but then i got the following error error: ‘var_SetInteger’ was not declared in this scope so i searched for the file in which var_SetInteger was defined and found that it was defined in vlc_variables.h so in included it and got the following error. What am i missing? ../vlc-0.9.10/include/vlc_variables.h:121: error: ‘__var_Create’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:121: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:121: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:121: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:121: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:122: error: ‘__var_Destroy’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:122: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:122: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:122: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:122: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:124: error: ‘__var_Change’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:124: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:124: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:124: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:124: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:126: error: ‘__var_Type’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:126: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:126: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:126: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:126: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:127: error: ‘__var_Set’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:127: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:127: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:127: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:127: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:128: error: ‘__var_Get’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:128: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:128: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:128: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:128: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:131: error: ‘__var_Command’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:131: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:131: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:131: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:131: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:133: error: expected constructor, destructor, or type conversion before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:171: error: ‘__var_AddCallback’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:171: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:171: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:171: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:171: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:172: error: ‘__var_DelCallback’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:172: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:172: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:172: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:172: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:173: error: ‘__var_TriggerCallback’ has not been declared ../vlc-0.9.10/include/vlc_variables.h:173: error: expected identifier before ‘(’ token ../vlc-0.9.10/include/vlc_variables.h:173: error: expected )' before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:173: error: expected ‘,’ or ‘...’ before ‘*’ token ../vlc-0.9.10/include/vlc_variables.h:173: error: expected constructor, destructor, or type conversion before ‘)’ token ../vlc-0.9.10/include/vlc_variables.h:201: error: ‘__var_SetInteger’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:201: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:201: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:201: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:201: error: expected primary-expression before ‘int’ ../vlc-0.9.10/include/vlc_variables.h:201: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:202: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:215: error: ‘__var_SetBool’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:215: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:215: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:215: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:215: error: expected primary-expression before ‘bool’ ../vlc-0.9.10/include/vlc_variables.h:215: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:216: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:229: error: ‘__var_SetTime’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:229: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:229: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:229: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:229: error: expected primary-expression before ‘i’ ../vlc-0.9.10/include/vlc_variables.h:229: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:230: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:243: error: ‘__var_SetFloat’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:243: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:243: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:243: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:243: error: expected primary-expression before ‘float’ ../vlc-0.9.10/include/vlc_variables.h:243: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:244: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:257: error: ‘__var_SetString’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:257: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:257: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:257: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:257: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:257: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:258: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:270: error: ‘__var_SetVoid’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:270: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:270: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:270: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:270: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:271: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:302: error: ‘__var_GetInteger’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:302: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:302: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:302: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:302: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:303: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:317: error: ‘__var_GetBool’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:317: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:317: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:317: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:317: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:318: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:332: error: ‘__var_GetTime’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:332: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:332: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:332: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:332: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:333: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:347: error: ‘__var_GetFloat’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:347: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:347: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:347: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:347: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:348: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:362: error: ‘__var_GetString’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:362: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:362: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:362: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:362: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:363: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:371: error: ‘__var_GetNonEmptyString’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:371: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:371: error: ‘obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:371: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:371: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:372: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:412: error: variable or field ‘__var_IncInteger’ declared void ../vlc-0.9.10/include/vlc_variables.h:412: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:412: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:412: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:424: error: variable or field ‘__var_DecInteger’ declared void ../vlc-0.9.10/include/vlc_variables.h:424: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:424: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:424: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:437: error: ‘__var_CreateGetInteger’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:437: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:437: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:437: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:437: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:438: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:449: error: ‘__var_CreateGetBool’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:449: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:449: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:449: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:449: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:450: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:461: error: ‘__var_CreateGetTime’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:461: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:461: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:461: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:461: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:462: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:473: error: ‘__var_CreateGetFloat’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:473: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:473: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:473: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:473: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:474: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:485: error: ‘__var_CreateGetString’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:485: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:485: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:486: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:486: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:487: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:492: error: ‘__var_CreateGetNonEmptyString’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:492: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:492: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:493: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:493: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:494: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:527: error: ‘__var_CreateGetIntegerCommand’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:527: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:527: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:527: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:527: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:528: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:540: error: ‘__var_CreateGetBoolCommand’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:540: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:540: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:540: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:540: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:541: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:553: error: ‘__var_CreateGetTimeCommand’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:553: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:553: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:553: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:553: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:554: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:566: error: ‘__var_CreateGetFloatCommand’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:566: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:566: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:566: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:566: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:567: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:579: error: ‘__var_CreateGetStringCommand’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:579: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:579: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:580: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:580: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:581: error: expected ‘,’ or ‘;’ before ‘{’ token ../vlc-0.9.10/include/vlc_variables.h:587: error: ‘__var_CreateGetNonEmptyStringCommand’ declared as an ‘inline’ variable ../vlc-0.9.10/include/vlc_variables.h:587: error: ‘vlc_object_t’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:587: error: ‘p_obj’ was not declared in this scope ../vlc-0.9.10/include/vlc_variables.h:588: error: expected primary-expression before ‘const’ ../vlc-0.9.10/include/vlc_variables.h:588: error: initializer expression list treated as compound expression ../vlc-0.9.10/include/vlc_variables.h:589: error: expected ‘,’ or ‘;’ before ‘{’ token src/transcribeWidget.cpp:859: warning: unused parameter ‘bytesSent’ src/transcribeWidget.cpp:859: warning: unused parameter ‘bytesTotal’ ../vlc-0.9.10/include/vlc_variables.h:201: warning: ‘__var_SetInteger’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:215: warning: ‘__var_SetBool’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:229: warning: ‘__var_SetTime’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:243: warning: ‘__var_SetFloat’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:257: warning: ‘__var_SetString’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:270: warning: ‘__var_SetVoid’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:302: warning: ‘__var_GetInteger’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:317: warning: ‘__var_GetBool’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:332: warning: ‘__var_GetTime’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:347: warning: ‘__var_GetFloat’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:362: warning: ‘__var_GetString’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:371: warning: ‘__var_GetNonEmptyString’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:437: warning: ‘__var_CreateGetInteger’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:449: warning: ‘__var_CreateGetBool’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:461: warning: ‘__var_CreateGetTime’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:473: warning: ‘__var_CreateGetFloat’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:485: warning: ‘__var_CreateGetString’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:492: warning: ‘__var_CreateGetNonEmptyString’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:527: warning: ‘__var_CreateGetIntegerCommand’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:540: warning: ‘__var_CreateGetBoolCommand’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:553: warning: ‘__var_CreateGetTimeCommand’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:566: warning: ‘__var_CreateGetFloatCommand’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:579: warning: ‘__var_CreateGetStringCommand’ defined but not used ../vlc-0.9.10/include/vlc_variables.h:587: warning: ‘__var_CreateGetNonEmptyStringCommand’ defined but not used

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• DynamicMethod for ConstructorInfo.Invoke, what do I need to consider?

  - by Lasse V. Karlsen

  My question is this: If I'm going to build a DynamicMethod object, corresponding to a ConstructorInfo.Invoke call, what types of IL do I need to implement in order to cope with all (or most) types of arguments, when I can guarantee that the right type and number of arguments is going to be passed in before I make the call? Background I am on my 3rd iteration of my IoC container, and currently doing some profiling to figure out if there are any areas where I can easily shave off large amounts of time being used. One thing I noticed is that when resolving to a concrete type, ultimately I end up with a constructor being called, using ConstructorInfo.Invoke, passing in an array of arguments that I've worked out. What I noticed is that the invoke method has quite a bit of overhead, and I'm wondering if most of this is just different implementations of the same checks I do. For instance, due to the constructor matching code I have, to find a matching constructor for the predefined parameter names, types, and values that I have passed in, there's no way this particular invoke call will not end up with something it should be able to cope with, like the correct number of arguments, in the right order, of the right type, and with appropriate values. When doing a profiling session containing a million calls to my resolve method, and then replacing it with a DynamicMethod implementation that mimics the Invoke call, the profiling timings was like this: ConstructorInfo.Invoke: 1973ms DynamicMethod: 93ms This accounts for around 20% of the total runtime of this profiling application. In other words, by replacing the ConstructorInfo.Invoke call with a DynamicMethod that does the same, I am able to shave off 20% runtime when dealing with basic factory-scoped services (ie. all resolution calls end up with a constructor call). I think this is fairly substantial, and warrants a closer look at how much work it would be to build a stable DynamicMethod generator for constructors in this context. So, the dynamic method would take in an object array, and return the constructed object, and I already know the ConstructorInfo object in question. Therefore, it looks like the dynamic method would be made up of the following IL: l001: ldarg.0 ; the object array containing the arguments l002: ldc.i4.0 ; the index of the first argument l003: ldelem.ref ; get the value of the first argument l004: castclass T ; cast to the right type of argument (only if not "Object") (repeat l001-l004 for all parameters, l004 only for non-Object types, varying l002 constant from 0 and up for each index) l005: newobj ci ; call the constructor l006: ret Is there anything else I need to consider? Note that I'm aware that creating dynamic methods will probably not be available when running the application in "reduced access mode" (sometimes the brain just won't give up those terms), but in that case I can easily detect that and just calling the original constructor as before, with the overhead and all.

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• Delegates in .NET: how are they constructed ?

  - by Saulius

  While inspecting delegates in C# and .NET in general, I noticed some interesting facts: Creating a delegate in C# creates a class derived from MulticastDelegate with a constructor: .method public hidebysig specialname rtspecialname instance void .ctor(object 'object', native int 'method') runtime managed { } Meaning that it expects the instance and a pointer to the method. Yet the syntax of constructing a delegate in C# suggests that it has a constructor new MyDelegate(int () target) where I can recognise int () as a function instance (int *target() would be a function pointer in C++). So obviously the C# compiler picks out the correct method from the method group defined by the function name and constructs the delegate. So the first question would be, where does the C# compiler (or Visual Studio, to be precise) pick this constructor signature from ? I did not notice any special attributes or something that would make a distinction. Is this some sort of compiler/visualstudio magic ? If not, is the T (args) target construction valid in C# ? I did not manage to get anything with it to compile, e.g.: int () target = MyMethod; is invalid, so is doing anything with MyMetod, e.g. calling .ToString() on it (well this does make some sense, since that is technically a method group, but I imagine it should be possible to explicitly pick out a method by casting, e.g. (int())MyFunction. So is all of this purely compiler magic ? Looking at the construction through reflector reveals yet another syntax: Func CS$1$0000 = new Func(null, (IntPtr) Foo); This is consistent with the disassembled constructor signature, yet this does not compile! One final interesting note is that the classes Delegate and MulticastDelegate have yet another sets of constructors: .method family hidebysig specialname rtspecialname instance void .ctor(class System.Type target, string 'method') cil managed Where does the transition from an instance and method pointer to a type and a string method name occur ? Can this be explained by the runtime managed keywords in the custom delegate constructor signature, i.e. does the runtime do it's job here ?

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• ASP.Net Webservice - Constructors with Parameters

  - by Ben

  Hi, I'm fairly new to WebService developement and have just set up my own webservice (ASP.Net 3.5, Visual Studio 2008 .asmx file). I can not find a way of setting up my webservice to take parameters on the constructor. If i create a constructor that takes parameters, it is not then shown when i hook up to the webservice from my application (it only shows a parameterless constructor). Am i missing something blatently obvious, or is this not possible (and why not)? Thanks.

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• constructors and inheritance in JS

  - by nandinga

  Hi all, This is about "inheritance" in JavaScript. Supose I create a constructor Bird(), and another called Parrot() which I make to "inherit" the props of Bird by asigning an instance of it to Parrot's prototype, like the following code shows: function Bird() { this.fly = function(){}; } function Parrot() { this.talk = function(){ alert("praa!!"); }; } Parrot.prototype = new Bird(); var p = new Parrot(); p.talk(); // Alerts "praa!!" alert(p.constructor); // Alerts the Bird function!?!?! After I've created an instance of Parrot, how comes that the .constructor property of it is Bird(), and not Parrot(), which is the constructor I've used to create the object? Thanks!!

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• Bug in the official Android Fragments training sample?

  - by Jeff Axelrod

  It seems to me that there must be a bug in the Android Fragments demo. As background, Fragments are apparently sometimes instantiated by the Android OS and thus need a public no-arg constructor: All subclasses of Fragment must include a public empty constructor. The framework will often re-instantiate a fragment class when needed, in particular during state restore, and needs to be able to find this constructor to instantiate it. If the empty constructor is not available, a runtime exception will occur in some cases during state restore. But the NewsReader demo from the official Android training on Fragments constructs the HeadlinesFragment class and configures it with setOnHeadlineSelectedListener(this) from NewsReaderActivity.onCreate(). If the Android OS re-instantiates this fragment, the mHeadlineSelectedListener field will be null because HeadlinesFragment doesn't save or restore its state. Is this a bug or am I missing something?

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• C# reflection instantiation

  - by NickLarsen

  I am currently trying to create a generic instance factory for which takes an interface as the generic parameter (enforced in the constructor) and then lets you get instantiated objects which implement that interface from all types in all loaded assemblies. The current implementation is as follows:     public class InstantiationFactory     {         protected Type Type { get; set; }         public InstantiationFactory()         {             this.Type = typeof(T);             if (!this.Type.IsInterface)             {                 // is there a more descriptive exception to throw?                 throw new ArgumentException(/* Crafty message */);             }         }         public IEnumerable GetLoadedTypes()         {             // this line of code found in other stack overflow questions             var types = AppDomain.CurrentDomain.GetAssemblies()                 .SelectMany(a = a.GetTypes())                 .Where(/* lambda to identify instantiable types which implement this interface */);             return types;         }         public IEnumerable GetImplementations(IEnumerable types)         {             var implementations = types.Where(/* lambda to identify instantiable types which implement this interface */                 .Select(x = CreateInstance(x));             return implementations;         }         public IEnumerable GetLoadedImplementations()         {             var loadedTypes = GetLoadedTypes();             var implementations = GetImplementations(loadedTypes);             return implementations;         }         private T CreateInstance(Type type)         {             T instance = default(T);             var constructor = type.GetConstructor(Type.EmptyTypes);             if (/* valid to instantiate test */)             {                 object constructed = constructor.Invoke(null);                 instance = (T)constructed;             }             return instance;         }     } It seems useful to me to have my CreateInstance(Type) function implemented as an extension method so I can reuse it later and simplify the code of my factory, but I can't figure out how to return a strongly typed value from that extension method. I realize I could just return an object:     public static class TypeExtensions     {         public object CreateInstance(this Type type)         {             var constructor = type.GetConstructor(Type.EmptyTypes);             return /* valid to instantiate test */ ? constructor.Invoke(null) : null;         }     } Is it possible to have an extension method create a signature per instance of the type it extends? My perfect code would be this, which avoids having to cast the result of the call to CreateInstance():     Type type = typeof(MyParameterlessConstructorImplementingType);     MyParameterlessConstructorImplementingType usable = type.CreateInstance();

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• Refactor throwing not null exception if using a method that has a dependency on a certain contructor

  - by N00b

  In the method below the second constructor accepts a ForumThread object which the IncrementViewCount() method uses. There is a dependency between the method and that particular constructor. Without extracting into a new private method the null check in IncrementViewCount() and LockForumThread() (plus other methods not shown) is there some simpler re-factoring I can do or the implementation of a better design practice for this method to guard against the use of the wrong constructor with these dependent methods? Thank you for any suggestions in advance. private readonly IThread _forumLogic; private readonly ForumThread _ft; public ThreadLogic(IThread forumLogic) : this(forumLogic, null) { } public ThreadLogic(IThread forumLogic, ForumThread ft) { _forumLogic = forumLogic; _ft = ft; } public void Create(ForumThread ft) { _forumLogic.SaveThread(ft); } public void IncrementViewCount() { if (_ft == null) throw new NoNullAllowedException("_ft ForumThread is null; this must be set in the constructor"); lock (_ft) { _ft.ViewCount = _ft.ViewCount + 1; _forumLogic.SaveThread(_ft); } } public void LockForumThread() { if (_ft == null) throw new NoNullAllowedException("_ft ForumThread is null; this must be set in the constructor"); _ft.ThreadLocked = true; _forumLogic.SaveThread(_ft); }

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• When do instance variables get initialized and values assigned?

  - by AKh

  When doees the instance variable get initialized? Is it after the constructor block is done or before it? Consider this example: public abstract class Parent { public Parent(){ System.out.println("Parent Constructor"); init(); } public void init(){ System.out.println("parent Init()"); } } public class Child extends Parent { private Integer attribute1; private Integer attribute2 = null; public Child(){ super(); System.out.println("Child Constructor"); } public void init(){ System.out.println("Child init()"); super.init(); attribute1 = new Integer(100); attribute2 = new Integer(200); } public void print(){ System.out.println("attribute 1 : " +attribute1); System.out.println("attribute 2 : " +attribute2); } } public class Tester { public static void main(String[] args) { Parent c = new Child(); ((Child)c).print(); } } OUTPUT: Parent Constructor Child init() parent Init() Child Constructor attribute 1 : 100 attribute 2 : null When the memory for the atribute 1 & 2 are allocated in the heap ? Curious to know why is attribute 2 is NULL ? Are there any design flaws?

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• Permission denied to access property 'toString'

  - by Anders

  I'm trying to find a generic way of getting the name of Constructors. My goal is to create a Convention over configuration framework for KnockoutJS My idea is to iterate over all objects in the window and when I find the contructor i'm looking for then I can use the index to get the name of the contructor The code sofar (function() { constructors = {}; window.findConstructorName = function(instance) { var constructor = instance.constructor; var name = constructors[constructor]; if(name !== undefined) { return name; } var traversed = []; var nestedFind = function(root) { if(typeof root == "function" || traversed[root]) { return } traversed[root] = true; for(var index in root) { if(root[index] == constructor) { return index; } var found = nestedFind(root[index]); if(found !== undefined) { return found; } } } name = nestedFind(window); constructors[constructor] = name; return name; } })(); var MyApp = {}; MyApp.Foo = function() { }; var instance = new MyApp.Foo(); console.log(findConstructorName(instance)); The problem is that I get a Permission denied to access property 'toString' Exception, and i cant even try catch so see which object is causing the problem Fiddle http://jsfiddle.net/4ZwaV/

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• JavaScript - Inheritance in Constructors

  - by j0ker

  For a JavaScript project we want to introduce object inheritance to decrease code duplication. However, I cannot quite get it working the way I want and need some help. We use the module pattern. Suppose there is a super element: a.namespace('a.elements.Element'); a.elements.Element = (function() { // public API -- constructor Element = function(properties) { this.id = properties.id; }; // public API -- prototype Element.prototype = { getID: function() { return this.id; } }; return Element; }()); And an element inheriting from this super element: a.namespace('a.elements.SubElement'); a.elements.SubElement = (function() { // public API -- constructor SubElement = function(properties) { // inheritance happens here // ??? this.color = properties.color; this.bogus = this.id + 1; }; // public API -- prototype SubElement.prototype = { getColor: function() { return this.color; } }; return SubElement; }()); You will notice that I'm not quite sure how to implement the inheritance itself. In the constructor I have to be able to pass the parameter to the super object constructor and create a super element that is then used to create the inherited one. I need a (comfortable) possibility to access the properties of the super object within the constructor of the new object. Ideally I could operate on the super object as if it was part of the new object. I also want to be able to create a new SubElement and call getID() on it. What I want to accomplish seems like the traditional class based inheritance. However, I'd like to do it using prototypal inheritance since that's the JavaScript way. Is that even doable? Thanks in advance! EDIT: Fixed usage of private variables as suggested in the comments. EDIT2: Another change of the code: It's important that id is accessible from the constructor of SubElement.

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• Send a variable on the heap to another thread

  - by user1201889

  I have a strange problem in C++. An address of a Boolean gets "destroyed" but it doesn't get touched. I know that there are beater way's to accomplish what I try to do, but I want to know what I do wrong. I have a main class; this main class contains a vector of another class. There is a strange problem when a new instance gets created of this object. This is how my code works: There will start a thread when the constructor gets called of the “2nd”object. This thread gets as Parameter a struct. This is the struct: struct KeyPressData { vector<bool> *AutoPressStatus; vector<int> *AutoPressTime; bool * Destroy; bool * Ready; }; The struct gets filled in the constructor: MultiBoxClient::MultiBoxClient() { //init data DestroyThread = new bool; ReadyThread = new bool; AutoThreadData = new KeyPressData; //Reseting data *DestroyThread = false; *ReadyThread = false; //KeyPressData configurating AutoThreadData->AutoPressStatus = &AutoPressStatus; AutoThreadData->AutoPressTime = &AutoPressTime; AutoThreadData->Destroy = DestroyThread; AutoThreadData->Ready = ReadyThread; //Start the keypress thread CreateThread(NULL,NULL,(LPTHREAD_START_ROUTINE)AutoKeyThread,AutoThreadData,NULL,NULL); } As long as the constructor is running will the program run fine. But when the constructor closes the address of the “AutoThreadData-Destroy” will get corrupted. The program will crash when I call the value of the pointer. void WINAPI AutoKeyThread(void * ThreadData) { KeyPressData * AutoThreadData = (KeyPressData*)ThreadData; while(true) { if(*AutoThreadData->Destroy == true) //CRASH { *AutoThreadData->Ready = true; return; } Sleep(100); } } What did I test: I logged the address of the AutoThreadData and the AutoThreadData-Destroy when the constrcutor is running and clossed; the AutoThreadData address is equal to AutoThreadData when the constructor is closed. So there is no problem here. The address of AutoThreadData-Destroy gets destroyed when the constructor is closed. But how can this happen? The Boolean is on the heap and the KeyPressData struct (AutoThreadData) is on the heap. Destroy before: 00A85328 Destroy after: FEEEFEEE Can someone maby explain why this crash? I know that I can send a pointer to my class to the thread. But I want to know what goes wrong here. That way I can learn from my mistakes. Could someone help me with this problem? Thanks!

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