Wouldn’t it be nice to have a simple attribute instead of backing field madness in Silverlight\/WPF? Just like this:<\/p>\n
\r\npublic class MainViewModel : ViewModelBase\r\n{\r\n [NotifyPropertyChanged]\r\n public string Title { get; set; }\r\n}\r\n<\/pre>\nYou can use PostSharp for that<\/a>, you should at least use lambda expressions instead of strings<\/a>.<\/p>\nHere’s how to do it without 3rd party software:<\/p>\n
1.
\nIn your project declare base view model<\/strong>:<\/p>\n\r\npublic class ViewModelBase : INotifyPropertyChanged\r\n{\r\n public event PropertyChangedEventHandler PropertyChanged\r\n = delegate { };\r\n\r\n protected void OnPropertyChanged(string propertyName)\r\n {\r\n this.PropertyChanged(\r\n this,\r\n new PropertyChangedEventArgs(propertyName));\r\n }\r\n};\r\n<\/pre>\n2.
\nDeclare the attribute<\/strong><\/p>\nIt will be used to mark properties that should raise the PropertyChanged event.<\/p>\n
\r\n[AttributeUsage(AttributeTargets.Property)]\r\npublic class NotifyPropertyChangedAttribute : Attribute\r\n{\r\n}\r\n<\/pre>\n3.
\nCreate new MSBuildTasks library project<\/strong> (it can be in different solution)<\/p>\nAdd references to:<\/p>\n
\n- Mono.Cecil.dll<\/li>\n
- Mono.Cecil.Pdb.dll (this needed so Cecil can updated pdb file, which is need for debugging the modified assembly)<\/li>\n
- MSBuild assemblies<\/li>\n<\/ul>\n
4.
\nCreate new MSBuild task<\/strong><\/p>\nIt will inject PropertyChanged event invocation on properties marked with NotifyPropertyChanged attribute.<\/p>\n
\r\nusing System;\r\nusing System.IO;\r\nusing Microsoft.Build.Framework;\r\nusing Microsoft.Build.Utilities;\r\nusing Mono.Cecil;\r\nusing Mono.Cecil.Cil;\r\n\r\nnamespace MSBuildTasks\r\n{\r\n public class NotifyPropertyChangedTask : Task\r\n {\r\n public override bool Execute()\r\n {\r\n InjectMsil();\r\n return true;\r\n }\r\n\r\n private void InjectMsil()\r\n {\r\n var assemblyDefinition = AssemblyDefinition.ReadAssembly(\r\n AssemblyPath,\r\n new ReaderParameters { ReadSymbols = true });\r\n\r\n var module = assemblyDefinition.MainModule;\r\n\r\n foreach (var type in module.Types)\r\n {\r\n foreach (var prop in type.Properties)\r\n {\r\n foreach (var attribute in prop.CustomAttributes)\r\n {\r\n string fullName = attribute.Constructor.DeclaringType.FullName;\r\n if (fullName.Contains("NotifyPropertyChanged"))\r\n {\r\n InjectMsilInner(module, type, prop);\r\n }\r\n }\r\n }\r\n }\r\n assemblyDefinition.Write(\r\n this.AssemblyPath,\r\n new WriterParameters { WriteSymbols = true });\r\n }\r\n\r\n private static void InjectMsilInner(\r\n ModuleDefinition module,\r\n TypeDefinition type,\r\n PropertyDefinition prop)\r\n {\r\n var msilWorker = prop.SetMethod.Body.GetILProcessor();\r\n var ldarg0 = msilWorker.Create(OpCodes.Ldarg_0);\r\n\r\n MethodDefinition raisePropertyChangedMethod =\r\n FindRaisePropertyChangedMethod(type);\r\n if (raisePropertyChangedMethod == null)\r\n throw new Exception(\r\n "RaisePropertyChanged method was not found in type "\r\n + type.FullName);\r\n\r\n var raisePropertyChanged = module.Import(\r\n raisePropertyChangedMethod);\r\n var propertyName = msilWorker.Create(\r\n OpCodes.Ldstr,\r\n prop.Name);\r\n var callRaisePropertyChanged = msilWorker.Create(\r\n OpCodes.Callvirt,\r\n raisePropertyChanged);\r\n\r\n msilWorker.InsertBefore(\r\n prop.SetMethod.Body.Instructions[\r\n prop.SetMethod.Body.Instructions.Count - 1],\r\n ldarg0);\r\n\r\n msilWorker.InsertAfter(ldarg0, propertyName);\r\n msilWorker.InsertAfter(\r\n propertyName,\r\n callRaisePropertyChanged);\r\n }\r\n\r\n private static MethodDefinition FindRaisePropertyChangedMethod(\r\n TypeDefinition type)\r\n {\r\n foreach (var method in type.Methods)\r\n {\r\n if (method.Name == "RaisePropertyChanged"\r\n && method.Parameters.Count == 1\r\n && method.Parameters[0].ParameterType.FullName\r\n == "System.String")\r\n {\r\n return method;\r\n }\r\n }\r\n if (type.BaseType.FullName == "System.Object")\r\n return null;\r\n return FindRaisePropertyChangedMethod(\r\n type.BaseType.Resolve());\r\n }\r\n\r\n [Required]\r\n public string AssemblyPath { get; set; }\r\n }\r\n}\r\n<\/pre>\n5.
\nCompile the task assembly<\/strong>,<\/p>\nand copy it to “$(SolutionDir)\/..\/lib\/MSBuild\/MSBuildTasks.dll” folder along with Mono.Cecil.dll and Mono.Cecil.Pdb.dll assemblies.<\/p>\n
4.
\nFinally modify your Silverlight\/WPF project (.csproj file)<\/strong>:<\/p>\n\r\n<project>\r\n ...\r\n <usingTask TaskName="MSBuildTasks.NotifyPropertyChangedTask" AssemblyFile="$(SolutionDir)..libMSBuildMSBuildTasks.dll" \/>\r\n <target Name="AfterCompile">\r\n <msbuildTasks.NotifyPropertyChangedTask AssemblyPath="$(ProjectDir)obj$(Configuration)$(TargetFileName)" \/>\r\n <\/target>\r\n<\/project>\r\n<\/pre>\nVoila! Enjoy!<\/p>\n