c# – 如何使用Mono.Cecil注入System.Object.Equals?
使用Mono.Cecil我想重写以下属性:
public string FirstName { get { return _FirstName; } set { _FirstName = value; } } 对此: public string FirstName { get { return _FirstName; } set { if (System.Object.Equals(_FirstName,value)) { return; } _FirstName = value; } } 这只是重写的内容,但它是我遇到问题的地方. 使用Reflector我可以看到以下代码根据需要重写属性,除了调用System.Object.Equals().如果期望IL代码是: call bool [mscorlib]System.Object::Equals(object,object) 但它被写成: call instance void RewriteSharp.Person::.ctor() 写入对System.Object.Equals的调用的代码是: setMethodWriter.InsertBefore( firstExistingInstruction,setMethodWriter.Create(OpCodes.Call,objectEqualsMethodReference)); 用于初始化objectEqualsMethodReference的方法是: private static MethodReference GetSystemObjectEqualsMethodReference( AssemblyDefinition assembly ) { var typeReference = assembly.MainModule.GetTypeReferences() .Single(t => t.FullName == "System.Object"); var typeDefinition = typeReference.Resolve(); var methodDefinition = typeDefinition.Methods.Single( m => m.Name == "Equals" && m.Parameters.Count == 2 && m.Parameters[0].ParameterType.Name == "Object" && m.Parameters[1].ParameterType.Name == "Object" ); return methodDefinition; } 在我看来,setMethodWriter.Create()或GetSystemObjectEqualsMethodReference()是不正确的,没有多少调试解决了这个问题. 正在编写的属性和重写属性的代码具有相同的框架目标. 3.5和4.0都失败了. 我正在使用master分支https://github.com/jbevain/cecil来构建Mono.Cecil. 完整的代码清单 using Mono.Cecil; using Mono.Cecil.Cil; using System; using System.Linq; namespace RewriteNotifyPropertyChanged { class Program { static void Main(string[] args) { var rewrite = "..RewriteSharp.dll"; var rewritten = "..RewritenSharp.dll"; var typeName = "Person"; var propertyName = "FirstName"; var assembly = AssemblyDefinition.ReadAssembly(rewrite); var typeDefinition = assembly.MainModule.Types.Single(t => t.Name == typeName); var propertyDefintion = typeDefinition.Properties .Single(p => p.Name == propertyName); var setMethodWriter = propertyDefintion.SetMethod.Body.GetILProcessor(); var backingFieldReference = GetBackingFieldReference(typeDefinition,propertyName); var objectEqualsMethodReference = GetSystemObjectEqualsMethodReference(assembly); var firstExistingInstruction = setMethodWriter.Body.Instructions[0]; setMethodWriter.InsertBefore( firstExistingInstruction,setMethodWriter.Create(OpCodes.Ldarg_0)); setMethodWriter.InsertBefore( firstExistingInstruction,setMethodWriter.Create(OpCodes.Ldfld,backingFieldReference)); setMethodWriter.InsertBefore( firstExistingInstruction,setMethodWriter.Create(OpCodes.Ldarg_1)); setMethodWriter.InsertBefore( firstExistingInstruction,objectEqualsMethodReference)); setMethodWriter.InsertBefore( firstExistingInstruction,setMethodWriter.Create(OpCodes.Brfalse_S,firstExistingInstruction)); setMethodWriter.InsertBefore( firstExistingInstruction,setMethodWriter.Create(OpCodes.Ret)); assembly.Write(rewritten,new WriterParameters { WriteSymbols = true }); Console.WriteLine("Done."); Console.ReadKey(); } private static MethodReference GetSystemObjectEqualsMethodReference( AssemblyDefinition assembly ) { var typeReference = assembly.MainModule.GetTypeReferences() .Single(t => t.FullName == "System.Object"); var typeDefinition = typeReference.Resolve(); var methodDefinition = typeDefinition.Methods.Single( m => m.Name == "Equals" && m.Parameters.Count == 2 && m.Parameters[0].ParameterType.Name == "Object" && m.Parameters[1].ParameterType.Name == "Object" ); return methodDefinition; } private static FieldReference GetBackingFieldReference( TypeDefinition typeDefinition,string propertyName ) { var fieldName = "_" + propertyName; var fieldReference = typeDefinition.Fields.Single(f => f.Name == fieldName); return fieldReference; } } } 解决方法
Cecil与System.Reflection不同,它区分了引用和定义,并且每个模块都有一个范围.这意味着您不能简单地使用自己内部另一个模块的MethodDefinition.你必须创建一个适当的引用.这是塞西尔术语中称为
importing的过程.
具体来说,GetSystemObjectEqualsMethodReference返回corlib中定义的方法,您需要在模块中创建对它的引用: 更换: var objectEqualsMethodReference = GetSystemObjectEqualsMethodReference(assembly); 通过: var objectEqualsMethodReference = assembly.MainModule.Import (GetSystemObjectEqualsMethodReference(assembly)); 修复IL应该可以使它工作. 此外,虽然我在,它的方法: private static MethodReference GetSystemObjectEqualsMethodReference(AssemblyDefinition assembly) { var typeReference = assembly.MainModule.GetTypeReferences() .Single(t => t.FullName == "System.Object"); var typeDefinition = typeReference.Resolve(); var methodDefinition = typeDefinition.Methods.Single( m => m.Name == "Equals" && m.Parameters.Count == 2 && m.Parameters[0].ParameterType.Name == "Object" && m.Parameters[1].ParameterType.Name == "Object" ); return methodDefinition; } 会写得更好: private static MethodReference GetSystemObjectEqualsMethodReference(AssemblyDefinition assembly) { var @object = assembly.MainModule.TypeSystem.Object.Resolve (); return @object.Methods.Single( m => m.Name == "Equals" && m.Parameters.Count == 2 && m.Parameters[0].ParameterType.MetadataType == MetadataType.Object && m.Parameters[1].ParameterType.MetadataType == MetadataType.Object); } 和 assembly.Write(rewritten,new WriterParameters { WriteSymbols = true }); 如果在阅读程序集时未传递新的ReaderParameters {ReadSymbols = true},则没有多大意义. (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |