16.4. Retrieving modules from an assembly

An assembly can consist of one or more modules.^[1] To obtain an array of modules in an assembly, you use System.Reflection.Assembly's GetModules method.

^[1] A module is a file containing IL codes but without a manifest. Each assembly must have one and only one manifest file regardless of the number of modules it contains.

Let's create an assembly (called Assm) containing two modules (Mod1 and Mod2) first. The following three code fragments do just that.

1: // Mod1.cs
2: public class Mod1{}

1: // Mod2.cs
2: public class Mod2{}

 1: // Assm.cs
 2: using System;
 3: using System.Reflection;
 4:
 5: public class Assm{
 6:   public static void Main(){
 7:     Assembly a = Assembly.LoadFrom("Assm.exe");
 8:     Module[] modules = a.GetModules();
 9:     foreach(Module m in modules)
10:       Console.WriteLine(m);
11:   }
12: }

If you are using csc.exe, compile the two module files Mod1.cs and Mod2.cs into module files first (module files end with a .netmodule extension). Use the /target:module option of csc.exe:

c:expt>csc /target:module Mod1.cs
c:expt>csc /target:module Mod2.cs

Mod1.netmodule and Mod2.netmodule will be created.

(You can also use the option shortcut /t:module instead of /target:module.)

Then compile Assm.cs by adding into it the two module files you have just created. Use the /addmodule option to do this. If there is more than one module to be added into the final assembly file, separate them using commas without any spaces:

c:expt>csc /addmodule:Mod1.netmodule,Mod2.netmodule Assm.cs

The assembly file Assm.exe will be created. When executed, Assm.exe will produce the following output.

c:expt>assm
Assm.exe
Mod1.netmodule
Mod2.netmodule

The Assm assembly contains three modules in all – the Assm class itself, Mod1, and Mod2. Their names are displayed by reflection.