Question

I’d like to know how best to program three different editions of my C# ASP.NET 3.5 application in VS2008 Professional (which includes a web deployment project).
I have a Light, Pro and Ultimate edition (or version) of my application.
At the moment I’ve put all in one solution with three build versions in configuration manager and I use preprocessor directives all over the code (there are around 20 such constructs in some ten thousand lines of code, so it’s overseeable):

#if light
//light code
#endif
#if pro
//pro code
#endif //etc...

I’ve read in stackoverflow for hours and thought to encounter how e.g. Microsoft does this with its different Windows editions, but did not find what I expected.
Somewhere there is a heavy discussion about if preprocessor directives are evil.

What I like with those #if-directives is:

• the side-by-side code of differences,
  so I will understand the code for the
  different editions after six months
• and the special benefit to NOT give
  out compiled code of other versions
  to the customer.

OK, long explication, repeated question:
What’s the best way to go?

Answer 1

I’d be tempted to manage the differences during runtime with different licences, and enable/disable features using that configuration. Why ?

1. you only have to build one deployable.
2. you can unit test this much more easily, rather than build 3 versions and test this.
3. users can upgrade and simply be sent a new licence. They won’t have to upgrade/reinstall.

You have to weigh this up against your concern for distributing a solution that your customers haven’t actually paid for (and can simply enable via an appropriately secure licence key).