Sunday, 28 February 2010

NDepend

I received an email the other day from Patrick Smacchia, the lead developer of probably the best known .NET dependency analysis tool NDepend a couple of days ago, letting me know that version 3.0 is now available.

It also pricked my conscious that a fair while back Patrick had given me a license for NDepend v2.0 and only asked that I post about my experiences using it. It is now way overdue for me to return the favour… so what are my thoughts?

First of all, what is it? As I understand it NDepend is a static analysis tool that looks at the dependencies between classes and assemblies. Whereas FxCop might look at individual lines of code to detect sub-optimal patterns, NDepend takes a step back and looks at the big picture of how your application is architected – especially how loosely coupled (or not) your classes are (which is normally a desirable aim).

Probably the main thing I like about NDepend is the dependency graph it can generate. I've found this useful both for getting a thumbnail sketch of your current solution (especially if it has evolved a bit over time), and also to a rough idea of the architecture of a legacy application that you've just been handed.

One other feature that appeals to my sense of keeping your code in good order is how it can highlight potential version mismatches between assemblies and also symbol files. When your build process becomes slightly more complicated this can be handy to ensure all your ducks are in the right row and version :-) The version differences may not be a problem for compiling and linking, but if your PDB file is wrong then you're going to get misleading or minimal stack trace information – something better avoided in the first place.

The final feature that can be quite illuminating for me is the dependencies matrix. This is a table (matrix) that shows the interdependencies between all your assemblies. Because it adds up the totals, you can quickly identify where an assembly may only have one (or even no) hard dependencies on another assembly and consider refactoring to reduce your coupling if appropriate.

There are also features of NDepend that to be honest I'm happy to know are there but haven't had a chance to make use of in a real way yet. It has a very comprehensive inbuilt query language, and could add some real value to a continuous integration build system – where you're keen to set some code quality benchmarks.

If you're still not convinced, there's a whole bunch of demo and tutorial videos on the NDepend site that can explain the range of features a lot better than I can.

Version 3.0 adds new features including:

  • Better integration with Visual Studio, including support for VS 2010
  • NDepend projects can now be a part of a Visual Studio solution
  • Improved performance
  • Integration with Reflector

In summary I have found NDepend to be a really useful tool to have in my toolkit, and I'd like to thank Patrick and his colleagues for the opportunity to have access to it.

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