CHAPTER 5 n VB 2008 AND THE CLR 95
Summary
In this chapter, we covered the essentials of how a VB program is compiled, packaged, and
executed. We looked at how your VB code gets compiled into IL and is then compiled on the
fly by the JIT compiler. One of the requirements for JIT compilation is an expressive and
extensible mechanism that the compiler can understand??”thus we have assemblies.
By packaging IL into assemblies that are self-documenting, both the CLR and the JIT
compiler have all the information they need to manage code execution. Private assemblies
make it possible to run multiple versions of code without having to worry about registry
entries, and shared assemblies provide the ability to access the functionality of a single assembly
from multiple applications.
In the next chapter, we??™ll jump into the important topic of interface-based, or contractbased,
programming.
CHAPTER 5 n VB 2008 AND THE CLR 96
Interfaces
An interface defines a contract between components. A contract, when applied to a type,
imposes a set of requirements on that type. Typically, this means a set of methods and properties
that any type implementing the interface is guaranteed to provide. Using interfaces, you can separate
the definition of your objects from their implementation.
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