C#: Can someone explain the practicalities of reflection? [duplicate]

Question

So I tried searching SO hoping someone had a good explanation of this, with no luck.

I asked another friend of mine a different question (which I've now forgotten) and his answer was simply "reflection" before he signed off.

I am still very new to the C# world, having been an amateur VB.net programmer (also JavaScript, ActionScript, and C), and am trying as hard as I can to grasp these advanced concepts.

There's lots of philosophical answers -- "application looking at itself" -- but they don't provide any practical hints on what is actually going on or how it is used within that context.

So, what is reflection, why is it important, and why/how do I use it?

Answer 1

Reflection provides the ability to determine things and execute code at runtime.

You don't have to use it if you don't want to, but it is extremely handy for dynamic behavior.

For example:

a) You can use reflection to configure your application by loading an external configuration file and starting services based on it. Your application wont have to know in advance about the classes that implement those services, as long as they conform to a specific interface or API.

b) Using reflection you can generate classes and code on the fly, which simplifies certain programming tasks since the programmer does not have to explicitly create all the needed code.

c) Reflection is also invaluable for programs that work by examining code. An example of that would be an IDE or a UI designer.

d) Reflection helps you reduce boilerplate code.

e) Reflection is handy for defining mini Domain Specific Languages (DSL) in your code.