Code generation in C#

I wrote my first code generator on the weekend. The real work - generating the C# class files - was trivial. Getting the generator into a state so that it could be easily used was more difficult.

There are a few ways you could do code generation in .NET. I explored:

• Console application that churns out ".cs" files
• Custom Tool for Visual Studio
• T4 Templates

I went with T4 Templates. They were a little obscure at first but provided the easiest entry point into using the code generator. You just build-up your source file and then right-click and select "Run Custom Tool" on the .tt file to generate the code.

I encounted a few issues when trying to write my template. They were:

• Extension methods can't be embedded into a T4 Template. There is a workaround. I ended up converting my extension methods into normal methods (I only had two).
• Accessing your assemblies is difficult in Visual Studio 2010. It has been explained very well. I managed to access my assemblies by writing something like <#@ assembly name="$(SolutionDir)..\DomainEntities\bin\Debug\Cpa.DomainEntities.dll" #>

The example T4 Templates I found on the Internet were a little more complex than what I wanted. (Examples should be as simple as possible.) I wanted to load a source file into memory and generate class files from that. Download my example template if you want something similar. It loads in a CSV file that has two columns (first column is the name of the class, second column the name of the property) and generates some puesdo-code of what the class files will eventually look like. I used this as my base template, then expanded it to create proper C# class files.