Quality

Your code base has a lot to tell you. The question is: How can you listen to it? You can identify code smells when you’re reading code or extending it, but this doesn’t give you an overview. After you have been working for a while in a project, you can name some of its strengths and weaknesses. But this approach takes a long time, relies on experience and is subjective. It would be nice if you could query a code base in a structured way. Basic search functionality from an IDE like Visual Studio isn’t powerful enough. NDepend allows you to query .Net code using LINQ syntax through CQLinq – Code Query LINQ. In this blog post we’ll discuss how to query your code base using CQLinq.

An Example

Since I like to learn from examples, let’s first see a simple, yet very powerful query. The following code detects classes that are candidates to be turned into structures. This is one of the default CQLinq rules.

from t in JustMyCode.Types where
  t.IsClass &&
 !t.IsGeneratedByCompiler &&
 !t.IsStatic &&
  t.SizeOfInst > 0 &&

  // Structure instance must not be too big,
  // else it degrades performance.
  t.SizeOfInst <= 16 &&
  // Must not have children
  t.NbChildren == 0 &&

  // Must not implement interfaces to avoid boxing mismatch
  // when structures implements interfaces.
  t.InterfacesImplemented.Count() == 0 &&

  // Must derive directly from System.Object
  t.DepthOfDeriveFrom("System.Object".AllowNoMatch()) == 1 &&

  // Structures should be immutable type.
  t.IsImmutable
select new { t, t.SizeOfInst, t.InstanceFields }

As you can see, the query is quite readable. Even if you don’t know the CQLinq syntax, you understand what it does. And since it’s based on Linq, it already seems familiar.

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Clean Code, Quality

How do you manage dependencies in your project? Since an image speaks a thousand words, I’ve always been a fan of visual management. Unfortunately, Visual Studio Professional doesn’t provide a way to do this. In the Premium and Enterprise editions you can visualize code dependencies on dependency graphs. But I don’t think this is enough. An architectural diagram with every assembly or namespace in my solution doesn’t tell me that much. It contains too much information.

Fortunately, there is a tool that can help you manage dependencies in the .Net world: NDepend (there is also a Java port – JArchitect). NDepend is a static analysis tool that, among other things, allows you to visualize dependencies. After I first ran NDepend on a project, I was overwhelmed with information. Then I took some time to play around and discover what can it tell me about my solution. NDepend integrates into Visual Studio quite nicely and points you in the right direction through tool tips and links. This is useful for people who prefer learning by doing. Aside from giving you information, it also tells you what to do with that information.

NDepend has two main views for managing dependencies: the Dependency Graph and the Dependency Structure Matrix. Apart from these, there is also an Abstractness vs Instability report that can be helpful. In this blog post, we’ll discuss some of the things that these views can tell you about your solution.

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Quality

In a previous blog post we discussed why building the right product is hard and some tips on how to achieve a high perceived integrity. But if you’re building a strategic solution that should support your business for many years, this is not enough. With time, new requirements get added, features change and team members might leave the project. This, together with hard deadlines, means that technical debt starts to incur, and the price of adding new features increases until someone says it will be easier to rebuild the whole thing from scratch. This isn’t a situation you’d like to be in, so that’s why it is important to build the product right.

Building the product right

In their book, Mary and Tom Poppendieck define this dimension of quality as the conceptual integrity of a product. Conceptual (internal) integrity means that the system’s central concepts work together as a smooth, cohesive whole.

How can you maintain the conceptual integrity of a product during its lifetime? You rely on communication, short feedback loops, transparency and empowered teams. These are the same principles that can lead to a high perceived integrity. The only difference is that you apply them at an architectural and code level. Continue Reading