Question

我正在尝试使用System.Reflection.Emit创建此C＃类。

private class MyTestData : IMyClonable
{
    private int _testValue = 0;
    public int testValue
    {
        get { return _testValue; }
        set { _testValue = value; }
    }

    public IMyClonable Clone()
    {
        MyTestData clone = new MyTestData();
        clone._testValue = _testValue;
        return clone ;
    }
}

必须从此界面创建此类：

public interface IMyTestData : IMyClonable
{
    int testValue { get; set; }
}

我已经制作了生成属性的代码，这项工作很好。但是当我尝试创建方法Clone（）时，我卡住了。我不知道如何创建这个类本身的实例并将其保存在局部变量中。以下是生成方法Clone（）的代码：

private static void MakeCloneMethod(Type componentType, TypeBuilder typeBuilder)
{
    ConstructorBuilder ctor = 
        typeBuilder.DefineDefaultConstructor(MethodAttributes.Public);

    MethodInfo cloneMethod = typeof(IMyClonable).GetMethod("Clone");
    MethodAttributes methodIlAttributes = 
        (cloneMethod.Attributes & ~MethodAttributes.Abstract) | MethodAttributes.Final;

    MethodBuilder cloneMthdBldr = typeBuilder.DefineMethod(
        "Clone", methodIlAttributes, typeof(IMyClonable), new Type[] { });
    ILGenerator ilgen = cloneMthdBldr.GetILGenerator();

    LocalBuilder returnValue = ilgen.DeclareLocal(typeBuilder.AsType());

    ilgen.Emit(OpCodes.Newobj, ctor);
    ilgen.Emit(OpCodes.Stloc_S, returnValue);

    CloneProperties(componentType, ilgen);

    ilgen.Emit(OpCodes.Ldloc_S);
    ilgen.Emit(OpCodes.Ret);

    typeBuilder.DefineMethodOverride(cloneMthdBldr, cloneMethod);
}

private static void CloneProperties(Type componentType, ILGenerator ilgen)
{
    PropertyInfo[] allProperties = GetPublicProperties(componentType);
    foreach (PropertyInfo propInfo in allProperties)
    {
        ilgen.Emit(OpCodes.Ldarg_0);
        ilgen.Emit(OpCodes.Ldfld, builders[propInfo]);
        ilgen.Emit(OpCodes.Stfld, builders[propInfo]);
        ilgen.Emit(OpCodes.Ldloc_0);
    }
}

当我尝试调用Clone（）方法时，我得到了System.InvalidProgramException。即使我评论方法CloneProperties（）的调用。我做错了什么？

Answer 1

我明白了！这是工作代码：

private static void MakeCloneMethod(Type componentType, TypeBuilder typeBuilder)
{
    Type thisType = typeBuilder.AsType();
    Type itype = typeof(IMyClonable);
    MethodInfo cloneMthd = itype.GetMethod("Clone");

    MethodBuilder cloneMthdBldr = typeBuilder.DefineMethod(
        cloneMthd.Name, cloneMthd.Attributes & ~MethodAttributes.Abstract, 
        itype, new Type[] {});
    typeBuilder.DefineMethodOverride(cloneMthdBldr, cloneMthd);

    ILGenerator gen = cloneMthdBldr.GetILGenerator();

    LocalBuilder returnValue = gen.DeclareLocal(thisType);

    gen.Emit(OpCodes.Newobj, typeBuilder.DefineDefaultConstructor(MethodAttributes.Public));
    gen.Emit(OpCodes.Stloc_S, returnValue);

    PropertyInfo[] allProperties = GetPublicProperties(componentType);
    foreach (PropertyInfo propInfo in allProperties)
    {
        gen.Emit(OpCodes.Ldloc_S, returnValue);
        gen.Emit(OpCodes.Ldarg_0);
        gen.Emit(OpCodes.Ldfld, builders[propInfo]);
        gen.Emit(OpCodes.Stfld, builders[propInfo]);
    }

    gen.Emit(OpCodes.Ldloc_S, returnValue);
    gen.Emit(OpCodes.Ret);
}

感谢Svick！

通过Reflection.Emmit创建类的实例

1 个答案: