我试图在运行时定义一个继承自已知类并实现接口的类型。
public class ParentClass
{
}
public interface IImplementMe
{
double Value{get;set}
}
这是显示我如何尝试实现目标的代码片段。
public class ClassBuilder
{
public Type Build()
{
try
{
AssemblyName assemblyName = new AssemblyName("DataBuilderAssembly");
AssemblyBuilder assemBuilder = Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
ModuleBuilder moduleBuilder = assemBuilder.DefineDynamicModule("DataBuilderModule");
TypeBuilder typeBuilder = moduleBuilder.DefineType("NewClass", TypeAttributes.Class, typeof(ParentClass));
typeBuilder.AddInterfaceImplementation(typeof(IImplementMe));
BuildProperty(typeBuilder, "Value", typeof(double));
Type type = typeBuilder.CreateType();
return type;
}
catch (Exception e)
{
return null;
}
}
private void BuildProperty(TypeBuilder typeBuilder, string name, Type type)
{
FieldBuilder field = typeBuilder.DefineField("m" + name, type, FieldAttributes.Private);
PropertyBuilder propertyBuilder = typeBuilder.DefineProperty(name, PropertyAttributes.None, type, null);
MethodAttributes getSetAttr = MethodAttributes.Public | MethodAttributes.HideBySig;
MethodBuilder getter = typeBuilder.DefineMethod("get_" + name, getSetAttr, type, Type.EmptyTypes);
ILGenerator getIL = getter.GetILGenerator();
getIL.Emit(OpCodes.Ldarg_0);
getIL.Emit(OpCodes.Ldfld, field);
getIL.Emit(OpCodes.Ret);
MethodBuilder setter = typeBuilder.DefineMethod("set_" + name, getSetAttr, null, new Type[] { type });
ILGenerator setIL = setter.GetILGenerator();
setIL.Emit(OpCodes.Ldarg_0);
setIL.Emit(OpCodes.Ldarg_1);
setIL.Emit(OpCodes.Stfld, field);
setIL.Emit(OpCodes.Ret);
propertyBuilder.SetGetMethod(getter);
propertyBuilder.SetSetMethod(setter);
}
}
出于某种原因,我在调用
typeBuilder.CreateType()
时收到“get_Value 方法未实现”异常。到目前为止还看不出背后的原因。
C# 隐式接口实现(通过名称匹配)只是为了方便;手动执行时,您需要使用 typeBuilder.DefineMethodOverride 将虚拟方法表中的每个关联起来,传入新的(生成的)方法和接口方法以满足。必须为您要实现的每个接口的每个方法完成此操作。
将您的线路更改为:
MethodAttributes getSetAttr = MethodAttributes.Public |
MethodAttributes.HideBySig | MethodAttributes.SpecialName | MethodAttributes.Virtual;
你的代码对我有用。 (需要虚拟。)
需要将其标记为虚拟的,并将实现显式绑定到接口:
// Associate the methods with the interface
foreach (var interfaceType in typeBuilder.ImplementedInterfaces)
{
var getMethod = interfaceType.GetMethod($"get_{fieldName}");
var setMethod = interfaceType.GetMethod($"set_{fieldName}");
if (getMethod != null)
{
typeBuilder.DefineMethodOverride(
getterBuilder,
getMethod);
}
if (setMethod != null)
{
typeBuilder.DefineMethodOverride(
setterBuilder,
setMethod);
}
}