What's the best way to manage a dependency tree in .NET?

Question

In my last project we used MSBuild as a scripting language. (yeah, really!) We also wrote hundreds of custom MSBuild tasks, for the parts that made more sense in C#. (I even wrote an MSBuild task to generate the boilerplate code for an MSBuild task. Yes, it consumed itself.)

While I don't recommend anyone else take this same approach, one of the things I found very helpful was the built-in dependency management. As you'd expect, it was easy to express dependency relationships and let MSBuild take care of satisfying them. For example, almost every step in our software required that a certain set of files be copied to a certain location. You could easily write:

Step1: CopyFiles
Step2: CopyFiles, Step1

and when you execute Step2, it would only copy the files once.

Building and satisfying a dependency tree is a pretty common in software. I wish the MSBuild team would take their dependency management code, decouple it from MSBuild, and move it in to the .NET Framework where anyone can use it. Baring that, what do you think is the best option for managing dependencies this way?

Answer 1

I think you could use an IOC container like Spring to get this kind of behavior.

Instantiate any task that must only run once as a singleton and have the constructor of the task object run the task. Then any object that comes along later with a dependency on that task will get a reference to the task that already ran and be able to get the results of that task or be able to infer that that task has already been run successfully.

In the spring config you would end up with many tasks chained together, each one references other tasks in its constructor config. This approach is the most flexible and you are not restricted to "tasks" or anything too heavy for that matter.

I'm guessing any workflow library also has similar concepts. But I am not really familiar with these.

I think for anything smaller, people must just roll their own object graph and interface using the visitor pattern and maybe a Dictionary to hold state.

Answer 2

Take a look at the Refix project on CodePlex. It stands for REference FIX and it works very nicely.