Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / xsp / System / Web / Util / FactoryGenerator.cs / 1305376 / FactoryGenerator.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //----------------------------------------------------------------------------- #if !DONTUSEFACTORYGENERATOR using System; using System.Reflection; using System.Reflection.Emit; using System.Threading; using System.Security; using System.Security.Permissions; namespace System.Web.Util { /* * Factory Generator class * A factory generator is useful for cases where a large number of late-bound * classes need to be instantiated. * * Normally, to create an instance of type t, you call the following code: * * ISomeInterface o = (ISomeInterface) Activator.CreateInstance(t); * * This assumes that the default constructor is used, and that the type t * implements the interface ISomeInterface. * * The factory generator, on the other hand, can use reflection emit APIs * to dynamically generate a class factory for t. The generated class has * the equivalent of the following code: * * class X : ISomeInterfaceFactory { * public ISomeInterface CreateInstance() { * return new t(); * } * } * * It then instantiates and returns an object of this type. You can then * call CreateInstance to create an instance of the type, which is * significantly faster. * * A single instance of a FactoryGenerator can generate factories for * multiple types. However, it builds all these types into a single * dynamically generated assembly. CLR implementation prevents this * assembly from being unloaded until the process exits. * * The FactoryGenerator is (almost) a templated type. It takes two * types in its constructor: * * returnedType is the type common to all classes for which factories * are to be generated. In the example above, this would be * ISomeInterface. * factoryInterface is the interface implemented by the dynamically * generated class factory, and should include a method named * CreateInstance, that takes no parameters and returns an object * of the type specified by returnedType. In the example above, * this would be ISomeInterfaceFactory. * * Copyright (c) 2003 Microsoft Corporation */ internal class FactoryGenerator { private Type _factoryInterface; private Type _returnedType; private MethodInfo _methodToOverride; private ModuleBuilder _dynamicModule = null; private Type[] _emptyParameterList = new Type[] { }; private Type[] _interfacesToImplement; internal FactoryGenerator() : this(typeof(object), typeof(IWebObjectFactory)) {} private FactoryGenerator(Type returnedType, Type factoryInterface) { _returnedType = returnedType; _factoryInterface = factoryInterface; // Get the CreateInstance method, and make sure it has // the correct signature. _methodToOverride = factoryInterface.GetMethod("CreateInstance", new Type[0]); if (_methodToOverride.ReturnType != _returnedType) { throw new ArgumentException(SR.GetString(SR.FactoryInterface)); } // This will be needed later, when building the dynamic class. _interfacesToImplement = new Type[1]; _interfacesToImplement[0] = factoryInterface; } // A type must be public and have a parameterless constructor, in order for us to be able to // create a factory for the type. Throws if either of these conditions are not true. internal static void CheckPublicParameterlessConstructor(Type type) { if (type == null) { throw new ArgumentNullException("type"); } if (!(type.IsPublic || type.IsNestedPublic)) { throw new InvalidOperationException(SR.GetString(SR.FactoryGenerator_TypeNotPublic, type.Name)); } ConstructorInfo constructor = type.GetConstructor(Type.EmptyTypes); if (constructor == null) { throw new InvalidOperationException(SR.GetString(SR.FactoryGenerator_TypeHasNoParameterlessConstructor, type.Name)); } } private static String GetUniqueCompilationName() { return Guid.NewGuid().ToString().Replace('-', '_'); } Type GetFactoryTypeWithAssert(Type type) { CheckPublicParameterlessConstructor(type); // Create the dynamic assembly if needed. Type factoryType; if (_dynamicModule == null) { lock (this) { if (_dynamicModule == null) { // Use a unique name for each assembly. String name = GetUniqueCompilationName(); AssemblyName assemblyName = new AssemblyName(); assemblyName.Name = "A_" + name; // Create a new assembly. AssemblyBuilder newAssembly = Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run, null, //directory to persist assembly true, //isSynchronized null //assembly attributes ); // Create a single module in the assembly. _dynamicModule = newAssembly.DefineDynamicModule("M_" + name); } } } // Give the factory a unique name. String typeName = GetUniqueCompilationName(); TypeBuilder factoryTypeBuilder = _dynamicModule.DefineType("T_" + typeName, TypeAttributes.Public, typeof(Object), _interfacesToImplement); // Define the CreateInstance method. It must be virtual to be an interface implementation. MethodBuilder method = factoryTypeBuilder.DefineMethod("CreateInstance", MethodAttributes.Public | MethodAttributes.Virtual, _returnedType, null); // Generate IL. The generated IL corresponds to "return new type()" // newobj// ret ILGenerator il = method.GetILGenerator(); ConstructorInfo cons = type.GetConstructor(Type.EmptyTypes); il.Emit(OpCodes.Newobj, cons); il.Emit(OpCodes.Ret); // Specify that this method implements CreateInstance from the inherited interface. factoryTypeBuilder.DefineMethodOverride(method, _methodToOverride); // Bake in the type. factoryType = factoryTypeBuilder.CreateType(); return factoryType; } internal IWebObjectFactory CreateFactory(Type type) { Debug.Trace("FactoryGenerator", "Creating generator for type " + type.FullName); Type factoryType = GetFactoryTypeWithAssert(type); // Create the type. This is the only place where Activator.CreateInstance is used, // reducing the calls to it from 1 per instance to 1 per type. return (IWebObjectFactory) Activator.CreateInstance(factoryType); } } } #endif // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- CngKeyCreationParameters.cs
- ResourceDescriptionAttribute.cs
- DesignerCategoryAttribute.cs
- TemplatePartAttribute.cs
- Effect.cs
- VariableAction.cs
- OdbcConnectionString.cs
- Stack.cs
- EndpointReference.cs
- WebServiceResponseDesigner.cs
- ProxyGenerationError.cs
- AssociationTypeEmitter.cs
- CacheHelper.cs
- OleStrCAMarshaler.cs
- JsonReader.cs
- BamlRecords.cs
- HelpInfo.cs
- TraceEventCache.cs
- RowUpdatedEventArgs.cs
- StateElementCollection.cs
- WorkflowInstanceExtensionManager.cs
- RemotingClientProxy.cs
- SqlBulkCopyColumnMappingCollection.cs
- TimeSpan.cs
- TcpAppDomainProtocolHandler.cs
- ClickablePoint.cs
- DescendantQuery.cs
- Vector3DAnimationUsingKeyFrames.cs
- ResourceReader.cs
- ObjectConverter.cs
- DocumentPageHost.cs
- CommonProperties.cs
- CustomAttributeBuilder.cs
- TypeSystem.cs
- GridViewColumnHeader.cs
- ElementProxy.cs
- MediaContext.cs
- AssemblyHash.cs
- XmlILOptimizerVisitor.cs
- Clipboard.cs
- _NetRes.cs
- DupHandleConnectionReader.cs
- DockAndAnchorLayout.cs
- CopyAttributesAction.cs
- RuntimeArgumentHandle.cs
- DBDataPermission.cs
- CodeValidator.cs
- DES.cs
- MediaEntryAttribute.cs
- ProviderUtil.cs
- EventLogLink.cs
- InkCanvas.cs
- XmlSchemaSimpleTypeList.cs
- EndpointIdentityExtension.cs
- SystemIcons.cs
- SupportsEventValidationAttribute.cs
- SqlUtils.cs
- FrameworkTextComposition.cs
- sqlser.cs
- DispatcherEventArgs.cs
- cryptoapiTransform.cs
- ExecutorLocksHeldException.cs
- XmlSchemaGroup.cs
- FormattedTextSymbols.cs
- MimeMapping.cs
- ReferenceService.cs
- SplineKeyFrames.cs
- MethodImplAttribute.cs
- DoubleCollectionConverter.cs
- ToolStripDropDownDesigner.cs
- TextParentUndoUnit.cs
- OptimalBreakSession.cs
- NullEntityWrapper.cs
- XmlNodeChangedEventArgs.cs
- Predicate.cs
- HitTestParameters.cs
- FacetValues.cs
- FieldMetadata.cs
- ImpersonationContext.cs
- APCustomTypeDescriptor.cs
- RetrieveVirtualItemEventArgs.cs
- ValueConversionAttribute.cs
- PageThemeCodeDomTreeGenerator.cs
- RemotingConfiguration.cs
- ToolStripPanelSelectionGlyph.cs
- ProcessHostServerConfig.cs
- BrushValueSerializer.cs
- TextBreakpoint.cs
- AssemblyBuilderData.cs
- SQLDouble.cs
- ValidationResult.cs
- ToolStripButton.cs
- EditorZoneDesigner.cs
- GreenMethods.cs
- UrlParameterReader.cs
- Rfc2898DeriveBytes.cs
- ClassDataContract.cs
- BinHexDecoder.cs
- BoolLiteral.cs
- DataListItemEventArgs.cs