23.6.txt

《Microsoft Visual C# .NET 2003开发技巧大全》源代码

Listing 23.6 Emitting IL Code
// add the hoarse method
MethodBuilder hoarseMethod = typeBuilder.DefineMethod( “MakeHoarse”,
MethodAttributes.Public, null, new Type[]{} );
ILGenerator gen = hoarseMethod.GetILGenerator();
// create labels for branching
Label endLoop = gen.DefineLabel();
Label beginLoop = gen.DefineLabel();
// create Console.WriteLine MethodInfo
MethodInfo writeLine = typeof(Console).GetMethod( “WriteLine”,
new Type[]{typeof(string)});
gen.DeclareLocal( typeof(int) );
gen.Emit( OpCodes.Ldc_I4_0 );
gen.Emit( OpCodes.Stloc_0 );
gen.Emit( OpCodes.Br_S, endLoop );
gen.MarkLabel( beginLoop );
gen.Emit( OpCodes.Ldarg_0 );
gen.Emit( OpCodes.Ldfld, soundFld );
gen.EmitCall( OpCodes.Call, writeLine, null );
gen.Emit( OpCodes.Ldloc_0 );
gen.Emit( OpCodes.Ldc_I4_1 );
gen.Emit( OpCodes.Add );
gen.Emit( OpCodes.Stloc_0 );
gen.MarkLabel( endLoop );
gen.Emit( OpCodes.Ldloc_0 );
gen.Emit( OpCodes.Ldarg_0 );
gen.Emit( OpCodes.Ldfld, countFld );
gen.Emit( OpCodes.Blt_S, beginLoop );
gen.EmitWriteLine(“...a muffled sound emanates...” );
gen.Emit( OpCodes.Ret );
// MakeHoarse IL Code
/*
IL_0000: ldc.i4.0
IL_0001: stloc.0
IL_0002: br.s IL_0013
IL_0004: ldarg.0
IL_0005: ldfld string ConsoleApplication1.Horse::Sound
IL_000a: call void [mscorlib]System.Console::WriteLine(string)
IL_000f: ldloc.0
IL_0010: ldc.i4.1
IL_0011: add
IL_0012: stloc.0
IL_0013: ldloc.0
IL_0014: ldarg.0
IL_0015: ldfld int32 ConsoleApplication1.Horse::Count
IL_001a: blt.s IL_0004
IL_001c: ldstr “...a muffled sound emanates from the animal.”
IL_0021: call void [mscorlib]System.Console::WriteLine(string)
IL_0026: ret
*/