Understanding CIL and the Role of Dynamic Assemblies

Summary

This chapter provided an overview of the syntax and semantics of CIL. Unlike higher-level managed languages such as C#, CIL does not simply define a set of keywords, but provides directives (used to define the structure of an assembly and its types), attributes (which further qualify a given directive), and opcodes (which are used to implementation type members). You were introduced to the CIL compiler (ilasm.exe) and learned how to alter the contents of a .NET assembly with new CIL code and also the basic process of building a .NET assembly using raw CIL.

The latter half of this chapter introduced you to the System. Reflection. Emit namespace. Using these types, you are able to emit a .NET assembly on the fly to memory. As well, if you so choose, you may persist this in-memory image to a physical file. Recall that many types of System. Reflection. Emit will automatically generate the correct CIL directives and attributes using friendly types such as ConstructorBuilder, TypeBuilder, and so forth. The ILGenerator type can be used to inject the necessary CIL opcodes into a given member. While we do have a number of helper types that attempt to make the process of programming with the CIL opcode set more palatable, you must have an understanding of CIL when programming with dynamic assemblies.