Question

我正在使用TypeBuilder创建类型。然后将这些类型用作泛型类中的参数。我想要做的是从名称中创建Type。泛型参数是动态的这一事实似乎是一个障碍。

static public class DynamicTypeTest
{
    public class Generic<T> { }

    static public void Test()
    {
        Type dynamicType = createDynamicType();
        Type genericType = typeof(Generic<>);

        // Generic<DynamicType>
        Type genericDynamicType = genericType.MakeGenericType(new Type[]{dynamicType});

        Debug.Assert(TypeFromName(genericDynamicType.FullName) == genericDynamicType);              // fail
        Debug.Assert(TypeFromName(genericDynamicType.AssemblyQualifiedName) == genericDynamicType); // fail
        Debug.Assert(TypeFromName(genericDynamicType.Name) == genericDynamicType);                  // fail

        // Generic<int>
        Type genericIntType = genericType.MakeGenericType(new Type[] { typeof(int) });

        Debug.Assert(TypeFromName(genericIntType.FullName) == genericIntType); // This succeeds. Replacing 'int' with a Type defined in another project also works
    }

    // This is the essence of what I want to do
    static private Type TypeFromName(string name)
    {
        return Assembly.GetExecutingAssembly().GetType(name);
    }

    static private Type createDynamicType()
    {
        AssemblyName assemblyName = new AssemblyName("DynamicAssembly");
        AssemblyBuilder assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
        ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule("DynamicModule");
        TypeAttributes typeAttributes = TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.AutoClass | TypeAttributes.AnsiClass;
        TypeBuilder typeBuilder = moduleBuilder.DefineType("DynamicType", typeAttributes, typeof(System.Object));

        return typeBuilder.CreateType();
    }
}

显然我知道如何从Type创建MakeGenericType，但在我正在使用的现实场景中，我不想（或者不能）修改类型名称，以便我可以单独创建类型并将它们拼凑在一起。

如何从Type名称重新创建此类string？

Answer 1

我突然意识到我应该使用Assembly.GetType()版本的错误引发Exception。它显示了一个FileNotFoundException，显然，在泛型参数中，只允许来自文件的程序集。为了解决这个问题，我从AssemblyResolve注册了AppDomain事件，并处理了在文件中找不到DynamicAssembly的情况。我的工作代码：

static public class DynamicTypeTest
{
    public class Generic<T> { }

    static public void Test()
    {
        AppDomain.CurrentDomain.AssemblyResolve += CurrentDomain_AssemblyResolve;

        Type dynamicType = createDynamicType();
        Type genericType = typeof(Generic<>);

        // Generic<DynamicType>
        Type genericDynamicType = genericType.MakeGenericType(new Type[]{dynamicType});

        Debug.Assert(TypeFromName(genericDynamicType.FullName) == genericDynamicType); // pass

        AppDomain.CurrentDomain.AssemblyResolve -= CurrentDomain_AssemblyResolve;
    }

    static Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
    {
        foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies())
        {
            AssemblyName assemblyName = assembly.GetName();

            if (args.Name == assemblyName.FullName)
            {
                return assembly;
            }
        }

        return null;
    }

    // This is the essence of what I want to do
    static private Type TypeFromName(string name)
    {
        try
        {
            return typeof(Generic<>).Assembly.GetType(name, true);
        }
        catch (Exception)
        {
            return null;
        }
    }

    static private Type createDynamicType()
    {
        AssemblyName assemblyName = new AssemblyName("DynamicAssembly");
        AssemblyBuilder assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
        ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule("DynamicModule");
        TypeAttributes typeAttributes = TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.AutoClass | TypeAttributes.AnsiClass;
        TypeBuilder typeBuilder = moduleBuilder.DefineType("DynamicType", typeAttributes, typeof(System.Object));

        return typeBuilder.CreateType();
    }

从TypeBuilder创建Bar时，从名称中检索类型Foo <bar>

1 个答案: