(My code is somewhat a mess of C# and VB.NET) I am trying to Emit class that looks as following:
public class SWTTFields
{
private string fieldName;
private int startPosition;
private int endPosition;
public static readonly SWTTFields ISO = new SWTTFields("ISO", 1, 2);
public static readonly SWTTFields EPC = new SWTTFields("EPC", 3, 4);
private SWTTFields(String fieldName, Int32 startPositon, Int32 endPositon)
{
this.fieldName = fieldName;
this.startPosition = startPositon;
this.endPosition = endPositon;
}
}
However, I am stack on assigning references to two static members. So far, I got this point (code below is in VB.NET, however I will gladly accept answers in VB.NET or C#):
Dim typeBuilder As TypeBuilder = GetTypeBuilder()
'Definition of three private variables
'TODO: you need one more private field that would represent "Bank" particular field belongs to
'Private String fieldName
Dim fieldName As FieldBuilder = typeBuilder.DefineField("fieldName",
GetType(String),
FieldAttributes.Private)
'Private Int32 startPosition
Dim startPosition As FieldBuilder = typeBuilder.DefineField("startPosition",
GetType(Int32),
FieldAttributes.Private)
'Private Int32 endPosition
Dim endPosition As FieldBuilder = typeBuilder.DefineField("endPosition",
GetType(Int32), FieldAttributes.Private)
'Type is taken from the current TypeBuilder
Dim ISO As FieldBuilder = typeBuilder.DefineField("ISO", typeBuilder.GetType, FieldAttributes.Public)
Dim EPC As FieldBuilder = typeBuilder.DefineField("EPC", typeBuilder.GetType, FieldAttributes.Public)
'Constructor parameters are
Dim constructorParams() As Type = {GetType(String), GetType(Int32), GetType(Int32)}
'constructor for the class
Dim ctorBuilder As ConstructorBuilder = typeBuilder.DefineConstructor(MethodAttributes.Public Or
MethodAttributes.SpecialName Or
MethodAttributes.RTSpecialName,
CallingConventions.Standard,
constructorParams)
Dim objType As Type = Type.GetType("System.Object")
'pulls out info about Object constructor. It will be called later
Dim objCtor As ConstructorInfo = objType.GetConstructor(Type.EmptyTypes)
'Generating code (some of the code and comments came from ConstructorBuilder class)
Dim ctorIL As ILGenerator = ctorBuilder.GetILGenerator()
'place "this" on the stack
ctorIL.Emit(OpCodes.Ldarg_0)
'Create instance of System.Object by invokign its ctor
ctorIL.Emit(OpCodes.Call, objCtor)
'store fieldName parameter
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_1)
ctorIL.Emit(OpCodes.Stfld, fieldName)
'store startPosition
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_2)
ctorIL.Emit(OpCodes.Stfld, startPosition)
'stored endPosition
ctorIL.Emit(OpCodes.Ldarg_0)
ctorIL.Emit(OpCodes.Ldarg_3)
ctorIL.Emit(OpCodes.Stfld, endPosition)
'Done. Return
ctorIL.Emit(OpCodes.Ret)
I haven't used TypeBuilder
myself so this is more of a hint than full code, but basically I believe you want TypeBuilder.DefineTypeInitializer
, and perform the assignments in there.
In other words, think of the class as looking like this, in terms of its static members:
public class SWTTFields
{
public static readonly SWTTFields ISO;
public static readonly SWTTFields EPC;
static SWTTFields()
{
ISO = new SWTTFields("ISO", 1, 2);
EPC = new SWTTFields("EPC", 3, 4);
}
}
(That's not exactly equivalent to the original code, due to the difference that a static constructor makes, but it's close enough.)
It looks like you already know how to generate the relevant IL for that type initializer body - just treat it like any other method/constructor body.
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