Real-World examples of Reflection

Question

What are your best examples of using Reflection in production code?

Answer 1

ASP.NET MVC inferring the action and controller to invoke from URL. Routing in general.

Answer 2

WPF Databinding:

1) Binding path "(TextBox.Text)" vs "Text"?

If you bind to a path called Text, WPF uses reflection to resolve the name. If you use the class-qualified name, binding avoids the reflection performance hit. Class-qualified names also allows binding to attached properties!

(via http://dotnet.org.za/rudi/archive/2008/03/25/10-things-i-didn-t-know-about-wpf-data-binding.aspx)

Answer 3

Most recently, I had to use reflection to load an assembly (in order to investigate its public types) from just the path of the assembly.

Answer 4

• NUnit Unit Testing Framework - Not very typical though
• CSLA uses reflection a lot
• Pretty much any Windows Forms app that supports plugins

Answer 5

Before Linq To Sql came out...I had to write my own ORM in .NET 2.0.

I used reflection heavily to reflect back on:

• Classes to their CRUD stored procedures
• Properties to their column names
• Which operations were valid for the class

I also used reflection to handle all variable assignment after the results were retreived (all classes inherited an ActiveRecord class that handled the calls into the DAL).

Rough stuff...but after some performance tuning it wasn't half bad.

Answer 6

My DAL is all reflection based. It reflects on the POCO properties to build SQL.

Answer 7

Pulling data out of an SQL table where you had an ID, a type, and other data

Then you could load "Chevrolet" and work with all of it's methods

Answer 8

Within a factory, we use reflection to either pass back a "Dummy" implementation of an interface or a real (hooked to the DB) implementation of an interface, based on the class specified in a properties file (in Java).

Answer 9

I did have occasion to write a Python O/R mapper on one at one point, but it was a proof of concept and never went into production.

I do quite a lot of work that makes extensive use of the system data dictionary on a DBMS (for example a generic slowly-changing dimension loader). It might be argued that this is not dissimilar to reflective programming in principle.

Finally, Python in all its forms is very easy to do reflection with. In fact, it's so good at this that I've used it to poke about with underlying API's in other languages - and use the reflective capabilities to query the underlying interfaces. I have done this with pretty much every reflective mechanism that exists in the Python world: CPython on Python API's and COM API's using makepy, Jython for java API's and IronPython for .Net API's.

Answer 10

In one of my recent apps, an add-in for Kofax Express, I have an option to OCR a file and output a PDF. Since the OCR tool I'm using has a runtime fee, I made the OCR part a seperate assembly. If the file exists, I show the OCR options and late bind the assembly and invoke the required methods and attach to the events with reflection. A simple plug in architecture without interfaces, and saves customers from having to pay royalty fees if they don't need to OCR; we just don't give them the OCR dll.