C# 使用基类和其他字段从TypeBuilder创建动态类型会生成异常
我试图基于只包含公共字段的现有类型创建一个动态类型。新的动态类型还必须继承另一个只具有完全实现的方法的基类型 我创建C# 使用基类和其他字段从TypeBuilder创建动态类型会生成异常,c#,inheritance,reflection,reflection.emit,typebuilder,C#,Inheritance,Reflection,Reflection.emit,Typebuilder,我试图基于只包含公共字段的现有类型创建一个动态类型。新的动态类型还必须继承另一个只具有完全实现的方法的基类型 我创建TypeBuilder指定基本类型,然后向其中添加公共字段,最后调用CreateType()。产生的错误消息是: 无法从程序集“MyDynamicsSembly”加载类型“InternalType”, Version=0.0.0.0,Culture=neutral,PublicKeyToken=null'因为字段 “first”没有给出明确的偏移量。” 对我来说,这意味着Creat
TypeBuilder
指定基本类型,然后向其中添加公共字段,最后调用CreateType()
。产生的错误消息是:
无法从程序集“MyDynamicsSembly”加载类型“InternalType”,
Version=0.0.0.0,Culture=neutral,PublicKeyToken=null'因为字段
“first”没有给出明确的偏移量。”
对我来说,这意味着CreateType
方法正在基类中查找公共字段“first”,这是一个问题,因为它不在基类中。为什么它认为添加的字段应该在基类中?还是我误解了例外
代码如下:
public class sourceClass
{
public Int32 first = 1;
public Int32 second = 2;
public Int32 third = 3;
}
public static class MyConvert
{
public static object ToDynamic(object sourceObject, out Type outType)
{
// get the public fields from the source object
FieldInfo[] sourceFields = sourceObject.GetType().GetFields();
// get a dynamic TypeBuilder and inherit from the base type
AssemblyName assemblyName
= new AssemblyName("MyDynamicAssembly");
AssemblyBuilder assemblyBuilder
= AppDomain.CurrentDomain.DefineDynamicAssembly(
assemblyName,
AssemblyBuilderAccess.Run);
ModuleBuilder moduleBuilder
= assemblyBuilder.DefineDynamicModule("MyDynamicModule");
TypeBuilder typeBuilder
= moduleBuilder.DefineType(
"InternalType",
TypeAttributes.Public
| TypeAttributes.Class
| TypeAttributes.AutoClass
| TypeAttributes.AnsiClass
| TypeAttributes.ExplicitLayout,
typeof(SomeOtherNamespace.MyBase));
// add public fields to match the source object
foreach (FieldInfo sourceField in sourceFields)
{
FieldBuilder fieldBuilder
= typeBuilder.DefineField(
sourceField.Name,
sourceField.FieldType,
FieldAttributes.Public);
}
// THIS IS WHERE THE EXCEPTION OCCURS
// create the dynamic class
Type dynamicType = typeBuilder.CreateType();
// create an instance of the class
object destObject = Activator.CreateInstance(dynamicType);
// copy the values of the public fields of the
// source object to the dynamic object
foreach (FieldInfo sourceField in sourceFields)
{
FieldInfo destField
= destObject.GetType().GetField(sourceField.Name);
destField.SetValue(
destObject,
sourceField.GetValue(sourceField));
}
// give the new class to the caller for casting purposes
outType = dynamicType;
// return the new object
return destObject;
}
好的,我在发帖后很快就明白了。我确实误读了错误信息。事实上,它与继承的基类无关 创建类型时,我指定了必需的属性“TypeAttributes.ExplicitLayout”。不幸的是,我没有意识到,在创建字段时,我还必须为每个字段添加一个偏移量。异常消息完全准确。对不起,误报了。更正代码如下:
public class SourceClass
{
public Int32 first = 1;
public Int32 second = 2;
public Int32 third = 3;
}
public static class MyConvert
{
public static object ToDynamic(object sourceObject, out Type outType)
{
Int32 fieldOffset = 0;
// get the public fields from the source object
FieldInfo[] sourceFields = sourceObject.GetType().GetFields();
// get a dynamic TypeBuilder and inherit from the base type
AssemblyName assemblyName
= new AssemblyName("MyDynamicAssembly");
AssemblyBuilder assemblyBuilder
= AppDomain.CurrentDomain.DefineDynamicAssembly(
assemblyName,
AssemblyBuilderAccess.Run);
ModuleBuilder moduleBuilder
= assemblyBuilder.DefineDynamicModule("MyDynamicModule");
TypeBuilder typeBuilder
= moduleBuilder.DefineType(
"InternalType",
TypeAttributes.Public
| TypeAttributes.Class
| TypeAttributes.AutoClass
| TypeAttributes.AnsiClass
| TypeAttributes.ExplicitLayout,
typeof(SomeOtherNamespace.MyBase));
// add public fields to match the source object
foreach (FieldInfo sourceField in sourceFields)
{
FieldBuilder fieldBuilder
= typeBuilder.DefineField(
sourceField.Name,
sourceField.FieldType,
FieldAttributes.Public);
fieldBuilder.SetOffset(fieldOffset);
fieldOffset++;
}
// create the dynamic class
Type dynamicType = typeBuilder.CreateType();
// create an instance of the class
object destObject = Activator.CreateInstance(dynamicType);
// copy the values of the public fields of the
// source object to the dynamic object
foreach (FieldInfo sourceField in sourceFields)
{
FieldInfo destField
= destObject.GetType().GetField(sourceField.Name);
destField.SetValue(
destObject,
sourceField.GetValue(sourceObject));
}
// give the new class to the caller for casting purposes
outType = dynamicType;
// return the new object
return destObject;
}
编辑:上面的代码不起作用。字段索引以字节为单位,因此当您增加偏移量时,应按字段大小执行,如下所示:
fieldOffset += sizeof(Int32);
为什么需要
ExplicitLayout
呢?请注意,第三方库使用非托管代码与可编程逻辑控制器(PLC)进行接口时需要它。我没有特别要求,可能是SequentialLayout就足够了。CreateType
为我抛出了一个错误:mscorlib.dll中的System.TypeLoadException。它说我的类型有一个无效的格式,为什么?vulkanino,只是一个建议,但你应该尝试开始一个新的步伐。大多数人不阅读已经标记为“已回答”的线程。祝您好运。@dtaylor,也许您应该使用TypeBuilder.SetParent(Type)
来告诉新继承的类它是继承的。您能演示一下如何使用该方法来动态(..)吗?谢谢您提供了这个非常好的主题。但是你不是在用基类复制一个新类,而不是继承基类吗?