Creating struct instead of class using ModuleBuilder.DefineType

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Marek - 13 Mar 2008 13:38 GMT

Hi
I am trying to dynamically create a struct using the following code:

TypeBuilder typeBuilder = moduleBuilder.DefineType("MyStruct",
TypeAttributes.Public);

It appears that this method will only ever create classes for me. Is there
any way of dynamically creating a struct? I noticed that other constructs
such as enums have their own equivalent define method (DefineEnum), but
couldn't see a way of doing this for structs.

I have to use a struct as this object is passed to a FORTRAN DLL which does
not like the class equivalent.

Best regards

Marek

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Marc Gravell - 13 Mar 2008 14:07 GMT

Have you tried using typeof(ValueType) as the parent? At the IL level,
both struct and class are IL classes - i.e. here is the sig from Int32
(IL view in reflector):

.class public sequential ansi serializable sealed beforefieldinit
Int32
extends System.ValueType
implements System.IComparable, System.IFormattable,
System.IConvertible, System.IComparable`1<int32>,
System.IEquatable`1<int32>

That seems to work - at least in a quick test CreateType().IsValueType
returned true.

Of course, you still might have some fun getting this new Type into
your external API...

Marc

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Marc Gravell - 13 Mar 2008 14:08 GMT

(example)

AssemblyName an = new AssemblyName("Foo");
AssemblyBuilder ab =
AppDomain.CurrentDomain.DefineDynamicAssembly(an,
AssemblyBuilderAccess.Run);
ModuleBuilder mb = ab.DefineDynamicModule("Foo");
TypeBuilder tb = mb.DefineType("Foo", TypeAttributes.Public |
TypeAttributes.Sealed | TypeAttributes.SequentialLayout |
TypeAttributes.Serializable, typeof(ValueType));
Type type = tb.CreateType();
bool isVal = type.IsValueType;

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Marek - 13 Mar 2008 14:22 GMT

Hi Marc
You're a star. That worked a treat thanks.

Nice use of the parent type parameter - I looked at it but didn't think of
using it in this way.

Best regards

Marek

> (example)
>
[quoted text clipped - 8 lines]
> Type type = tb.CreateType();
> bool isVal = type.IsValueType;

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Creating struct instead of class using ModuleBuilder.DefineType

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