This is a learning exercise. I created a method that takes a Foo and a string and sets the A property. I used the Reflector disassembly to make the following emit code. The disassembly looks like this:
.method private hidebysig static void Spork(class ConsoleTesting.Foo f, string 'value') cil managed
{
.maxstack 8
L_0000: ldarg.0
L_0001: ldarg.1
L_0002: callvirt instance void ConsoleTesting.Foo::set_A(string)
L_0007: ret
}
Ok, so I modeled my emit code after that:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.Reflection.Emit;
namespace ConsoleTesting
{
class Foo
{
public string A { get; set; }
}
class Program
{
static Action<Foo, string> GenMethodAssignment(string propName)
{
MethodInfo setMethod = typeof(Foo).GetMethod("get_" + propName);
if (setMethod == null)
throw new InvalidOperationException("no property setter available");
Type[] argTypes = new Type[] { typeof(Foo), typeof(String) };
DynamicMethod method = new DynamicMethod("__dynamicMethod_Set_" + propName, null, argTypes, typeof(Program));
ILGenerator IL = method.GetILGenerator();
IL.Emit(OpCodes.Ldarg_0);
IL.Emit(OpCodes.Ldarg_1);
IL.Emit(OpCodes.Callvirt, setMethod);
IL.Emit(OpCodes.Ret);
method.DefineParameter(1, ParameterAttributes.In, "instance");
method.DefineParameter(2, ParameterAttributes.In, "value");
Action<Foo, string> retval = (Action<Foo, string>)method.CreateDelegate(typeof(Action<Foo, string>));
return retval;
}
static void Main(string[] args)
{
Foo f = new Foo();
var meth = GenMethodAssignment("A");
meth(f, "jason");
Console.ReadLine();
}
}
I'm getting this exception:
JIT Compiler encountered an internal limitation.
What the krunk does that mean, and how do I fix it?
EDIT:
I thought maybe it's because the target method is private, but I'm not so sure. From the DynamicMethod MSDN page:
The following code example creates a DynamicMethod that is logically associated with a type. This association gives it access to the private members of that type.
Well I figured it out. Changing
IL.Emit(OpCodes.Callvirt, setMethod);
to
IL.Emit(OpCodes.Call, setMethod);
fixed it. I don't know why the disassembly showed CallVirt, but eh.