C# 4 and .NET 4

C r e a t i n g a s s e m b l i e s ❘ 435
In addition to using ildasm , the .NET Refl ector is another great tool to use to analyze
assemblies. The .NET Refl ector allows type and member search, and call and callee
graphs, and decompiles IL code to C#, C++, or Visual Basic. You can download this
tool from www.redgate.com/products/reflector .
CreaTing assemblies
Now that you know what assemblies are, it is time to build some. Of course, you have already built
assemblies in previous chapters, because a .NET executable counts as an assembly. This section looks at
special options for assemblies.
Creating modules and assemblies
All C# project types in Visual Studio create an assembly. Whether you choose a DLL or EXE project type,
an assembly is always created. With the command - line C# compiler csc, it ’ s also possible to create modules.
A module is a DLL without assembly attributes (so it ’ s not an assembly, but it can be added to assemblies at
a later time). The command :
csc /target:module hello.cs
creates a module hello.netmodule . You can view this module using ildasm .
A module also has a manifest, but there is no .assembly entry inside the manifest (except for the external
assemblies that are referenced) because a module has no assembly attributes. It ’ s not possible to confi gure
versions or permissions with modules; that can be done only at the assembly scope. You can fi nd references
to assemblies in the manifest of the module. With the /addmodule option of csc , it ’ s possible to add
modules to existing assemblies.
To compare modules to assemblies, create a simple
class A and compile it by using the following
command:
csc /target:module A.cs
The compiler generates the fi le A.netmodule ,
which doesn ’ t include assembly information (as
you can see using ildasm to look at the manifest
information). The manifest of the module shows the
referenced assembly mscorlib and the .module entry
in Figure 18 - 4.
Next, create an assembly B, which includes the
module A.netmodule . It ’ s not necessary to have a
source fi le to generate this assembly. The command to
build the assembly is:
csc /target:library /addmodule:A.netmodule /out:B.dll
figure 18-4
Looking at the assembly using ildasm , you can fi nd only a manifest. In the manifest, the assembly
mscorlib is referenced. Next, you see the assembly section with a hash algorithm and the version. The
number of the algorithm defi nes the type of the algorithm that was used to create the hash code of
the assembly. When creating an assembly programmatically it is possible to select the algorithm. Part of
the manifest is a list of all modules belonging to the assembly. In Figure 18 - 5 you see .file A.netmodule ,
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