Convert from Type to TypeBuilder

问题

I'm creating a class on runtime and some of the types are already created inside the ModuleBuilder and I would like to reused them, but I only have the Type and not the TypeBuilder (Which is what I need in order to change it)

Is there a way to convert from Type to TypeBuilder?

Type moduleType = ModuleBuilder.GetType(inXmlTemplateProperty.PropertyName);
        if (moduleType == null)
        {
            TypeBuilder newClass = ModuleBuilder.DefineType(inXmlTemplateProperty.PropertyName,
                                                            TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.Serializable);

            newClass.SetClassAttributes(inXmlTemplateProperty);

            return newClass;
        }

        return (TypeBuilder)moduleType;

Any suggestion is welcome, thanks in advance.

回答1:

TypeBuilder is a derived type of Type (via intermediate class TypeInfo).

So you can cast a TypeBuilder into a Type. But not the other way around.

You need to use the highest common level of abstraction (Type).

Do not cast moduleType into a TypeBuilder. Later on, you will be able to check if the type has been already created or not, using code like that :

class Program
{
    private static Type GetSomeTypePending(string typeName)
    {
        AssemblyBuilder ab = AppDomain.CurrentDomain.DefineDynamicAssembly(new AssemblyName("toto.dll"), AssemblyBuilderAccess.RunAndSave);
        ModuleBuilder mb = ab.DefineDynamicModule("toto.dll");
        TypeBuilder tb = mb.DefineType(typeName);
        return tb;
    }

    private static Type GetSomeTypeCreated(string typeName)
    {
        AssemblyBuilder ab = AppDomain.CurrentDomain.DefineDynamicAssembly(new AssemblyName("toto.dll"), AssemblyBuilderAccess.RunAndSave);
        ModuleBuilder mb = ab.DefineDynamicModule("toto.dll");
        TypeBuilder tb = mb.DefineType(typeName);
        tb.CreateType(); // do not return the created type, 
        return tb;       // return the typebuilder
    }

    static void Main(string[] args)
    {
        Type foo = GetSomeTypePending("tutu");
        Type foo2 = GetSomeTypeCreated("tutu");
        if (IsPendingTypeBuilder(foo))
        {
            Console.WriteLine("foo not yet created");
        }
        else
        {
            Console.WriteLine("foo created");
        }
        if (IsPendingTypeBuilder(foo2))
        {
            Console.WriteLine("foo2 not yet created");
        }
        else
        {
            Console.WriteLine("foo2 created");
        }
    }

    private static bool IsPendingTypeBuilder(Type foo)
    {
        return (foo is TypeBuilder) && !((foo as TypeBuilder).IsCreated());
    }
}

回答2:

some of the types are already created inside the ModuleBuilder and I would like to reuse them

You can't. As soon as you call TypeBuilder.CreateType, the type becomes frozen. Even if you could get access to the TypeBuilder, you wouldn't be able to modify the type.

来源：https://stackoverflow.com/questions/44675588/convert-from-type-to-typebuilder