System.Reflection.Emit的一个很重要的发现.

在同一个ModuleBuilder里, DefineType并且CreateType之后, 是可以继续DefineType的..

这样可以防止编译多次代码导致的AssemblyBuilder过多的问题. 现在只需要1个AssemblyBuilder就够了.

这个发现对于WEB框架非常有意义. 因为WEB框架包含大量的脚本文件. 有了这个特征, 脚本文件可以很放心地分开来编译了

 

using System;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Reflection.Emit;


static public class EmitTest
{
    static public void Go()
    {
        AssemblyBuilder asm = AppDomain.CurrentDomain.DefineDynamicAssembly(
            new AssemblyName("EmitTest"), AssemblyBuilderAccess.Run);
        ModuleBuilder mdl=asm.DefineDynamicModule("EmitTestModule");

        RunType(mdl, "Type1", "Method1", "Hello");
        RunType(mdl, "Type2", "Method2", "World");
    }

    private static void RunType(ModuleBuilder mdl,string typename
        ,string methodname,string writestring)
    {
        TypeBuilder t1 = mdl.DefineType(typename);
        MethodBuilder mb1 = t1.DefineMethod(methodname
            , MethodAttributes.Static | MethodAttributes.Public, typeof(void), new Type[] { });
        ILGenerator g1 = mb1.GetILGenerator();
        g1.Emit(OpCodes.Ldstr, writestring);
        g1.Emit(OpCodes.Call, typeof(EmitTest).GetMethod("WriteLine"));
        MethodInfo mi1 = t1.CreateType().GetMethod(methodname);
        mi1.Invoke(null, null);
    }

    [System.Runtime.CompilerServices.MethodImpl(
        System.Runtime.CompilerServices.MethodImplOptions.NoInlining)]
    static public void WriteLine(string str)
    {
        MethodBase caller=new System.Diagnostics.StackFrame(1).GetMethod();
        Console.WriteLine(caller.DeclaringType.Assembly.FullName);
        Console.WriteLine(str);
    }
}