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
- BamlLocalizabilityResolver.cs
- InvalidDataContractException.cs
- BindingExpressionUncommonField.cs
- Typeface.cs
- HostedHttpRequestAsyncResult.cs
- sqlcontext.cs
- TraceUtils.cs
- WebPartZoneCollection.cs
- FileSystemEventArgs.cs
- XmlUtf8RawTextWriter.cs
- WebPartDisplayModeCancelEventArgs.cs
- AttachedAnnotation.cs
- TableLayout.cs
- OrderByQueryOptionExpression.cs
- SimpleLine.cs
- DirectionalLight.cs
- DbBuffer.cs
- DataGridCheckBoxColumn.cs
- SharedStatics.cs
- ServiceProviders.cs
- Selection.cs
- TableLayoutColumnStyleCollection.cs
- ScrollItemProviderWrapper.cs
- Bits.cs
- TemplateColumn.cs
- VirtualPathProvider.cs
- WindowsEditBoxRange.cs
- ColorAnimation.cs
- _SslState.cs
- CodeSubDirectoriesCollection.cs
- ToolStripPanelCell.cs
- OdbcError.cs
- ChildrenQuery.cs
- SettingsProperty.cs
- DBCommandBuilder.cs
- ProgressBarAutomationPeer.cs
- BaseCollection.cs
- DataSysAttribute.cs
- ContentWrapperAttribute.cs
- WizardStepBase.cs
- InfoCardProofToken.cs
- CachingHintValidation.cs
- GridViewRow.cs
- CLSCompliantAttribute.cs
- ParameterCollection.cs
- BigInt.cs
- TdsEnums.cs
- sqlser.cs
- MobileFormsAuthentication.cs
- DataGrid.cs
- ClientSession.cs
- ByteRangeDownloader.cs
- ProjectedWrapper.cs
- ProxyWebPart.cs
- JoinCqlBlock.cs
- DATA_BLOB.cs
- CodeFieldReferenceExpression.cs
- FutureFactory.cs
- CharacterBufferReference.cs
- FindCriteriaCD1.cs
- ProtectedConfiguration.cs
- ListDictionaryInternal.cs
- AssociationSetMetadata.cs
- StructuredTypeEmitter.cs
- ObjectDataSourceView.cs
- DatePickerTextBox.cs
- SoapElementAttribute.cs
- OSFeature.cs
- BrowserCapabilitiesFactory35.cs
- ControlBuilderAttribute.cs
- RectAnimation.cs
- TableRow.cs
- ObfuscationAttribute.cs
- LocalBuilder.cs
- SettingsPropertyNotFoundException.cs
- XmlCharCheckingWriter.cs
- XmlArrayAttribute.cs
- StaticContext.cs
- datacache.cs
- DecoderExceptionFallback.cs
- DivideByZeroException.cs
- FormClosedEvent.cs
- JournalEntryStack.cs
- FormViewCommandEventArgs.cs
- ElementUtil.cs
- DataPagerFieldCollection.cs
- DocumentScope.cs
- ThemeDirectoryCompiler.cs
- AttachedPropertyBrowsableAttribute.cs
- UriTemplateTableMatchCandidate.cs
- StorageRoot.cs
- CollaborationHelperFunctions.cs
- LoginCancelEventArgs.cs
- RichTextBox.cs
- Label.cs
- DesignerForm.cs
- KeyboardNavigation.cs
- QilUnary.cs
- ServiceBusyException.cs
- ConfigXmlElement.cs