I’ve been working on a side project with a good friend and it uses T4 templates fairly heavily for wrapping database code (no, we couldn’t use EF for this when we started – we might look at it again later though) and for building up a nice wrapper for templated email. It worked like a champ, until I decided to do a bit of code cleanup to make it more aesthetically pleasing to myself. I was getting concerned because the code generated by the templates was somewhere north of 20,000 lines, declared well north of 100 separate classes with dozens of interfaces and lots of logic for interacting with the database (and with caching). It was all beautiful, clean, eloquent code (ok, I’m lying, but it wasn’t ugly enough that I hated it) and did its job remarkably well. I heartily recommend the Tangible T4 Text editor plugin for Visual Studio, as it makes a lot of this code work quite smoothly and pretty much never gave me a problem (I had to look up which tool I was using – I promise you I could remember off the top of my head if it broke regularly).