I’ve been working on a few utility type applications lately (more on them later, once they’re firmed up), but one thing I’ve found incredibly useful for certain projects is ILMerge.

If you’re not familiar with it, ILMerge is a utility that essentially can combine two or more .net assemblies into a single assembly, and reducing an application’s footprint is something I’m particularly passionate about!

In the past, I’ve always created postbuild steps that included executing ILMerge as just a command line post build process, but doing it this way has always been problematic. To start, debugging in the IDE tends to be compromised at best, and not possible at worst. Plus it just never felt clean.

In researching the problem, I ran across three blog posts that have provided more than enough info to get me past the Post Build process and actually integrate ILMerge directly into the build process itself, and one very intriguing alternative.

First, Scott Hanselman wrote about his experiences using ILMerge to merge a VB.net assembly into an otherwise C# project back in 2007. A great article and a fantastic first step.

Then, I came across Daniel Fortunov’s  article about integrating ILMerge into the VS build process. His example is also very good and a little cleaner, I’d say than Scott’s approach, but both articles are definitely worth checking out if you find yourself needing this kind of thing.

Lastly, Jeffrey Richter wrote a terrifically short but incredibly eye-popping article about a technique to load .net assemblies dynamically from binary resources baked into a single assembly at compile time. Very simple and clean. A great technique to have in your toolbox if the need ever arises.

For my part, I’ve used the ILMerge technique to merge Mono.Cecil.dll (a C# library from the mono project for directly altering .net assemblies) into a VB.net utility that can repackage portions of an assembly’s PDB file directly into the assembly’s EXE or DLL file, to supply line numbers during the rendering of an exception’s stack trace without actually have to provide a PDB (and all the additional metadata about your assembly) to your client. A fantastic debugging technique and one that I’ve been working with (off and on) for several years now. I’ll write about it in more detail later.