Tag: object-oriented

The Dimensions of Navigation in Object-Oriented Code

One powerful aspects of modern software development is how we move through our code. In object-oriented programming (OOP), understanding relationships between classes, interfaces, methods, and tests is important. But it is not just about reading code; it is about navigating it effectively.

This article explores the key movement dimensions that help developers work efficiently within OOP codebases. These dimensions are not specific to any tool but reflect the conceptual paths developers regularly take to understand and evolve code.

1. Hierarchy Navigation: From Parent to Subtype and Back

In object-oriented systems, inheritance and interfaces create hierarchies. One essential navigation dimension allows us to move upward to a superclass or interface, and downward to a subclass or implementing class.

This dimension is valuable because:

  • Moving up let us understand general contracts or abstract logic that governs behavior across many classes.
  • Moving down help us see specific implementations and how abstract behavior is concretely realized.

This help us maintain a clear overview of where we are within the hierarchy.

2. Behavioral Navigation: From Calls to Definitions and Back

Another important movement is between where methods are defined and where they are used. This is less about structure and more about behavior—how the system flows during execution.

Understanding this movement helps developers:

  • Trace logic through the system from the point of use to its implementation.
  • Identify which parts of the system rely on a particular method or class.
  • Assess how a change to a method might ripple through the codebase.

This navigation is useful when debugging, refactoring, or working in unfamiliar code.

3. Validation Navigation: Between Code and its Tests

Writing automated tests is a fundamental part of software development. Tests are more than just safety nets—they also serve as valuable guides for understanding and verifying how code is intended to behave. Navigating between a class and its corresponding test forms another important dimension.

This movement enables developers to:

  • Quickly validate behavior after making changes.
  • Understand how a class is intended to be used by seeing how it is tested.
  • Improve or add new tests based on recent changes.

Tight integration between code and test supports confident and iterative development, especially in test-driven workflows.

4. Utility Navigation: Supporting Movements that Boost Productivity

Beyond the main three dimensions, there are several supporting movements that contribute to developer efficiency:

  • Searching across the codebase to find any occurrence of a class, method, or term.
  • Generating boilerplate code, like constructors or property accessors, to reduce repetitive work.
  • Code formatting and cleanup, which helps maintain consistency and readability.
  • Autocompletion, which reduces cognitive load and accelerates writing.

These actions do not directly reflect code relationships but enhance how smoothly we can move within and around the code, keeping us focused on solving problems rather than managing structure.

Conclusion: Movement is Understanding

In object-oriented systems, navigating through your codebase along different dimensions provides essential insight for understanding, debugging, and improving your software.

Mastering these dimensions transforms your workflow from reactive to intuitive, allowing you to see code not just as static text, but as a living system you can navigate, shape, and grow.

In an upcoming post, I will take the movement dimensions discussed here and show how they are practically supported in IDEs like Eclipse and IntelliJ IDEA.

Object Calisthenics On Existing Projects?

A few days ago we discussed Object Calisthenics which where introduced by Jeff Bay in an article for the ThoughtWorks Anthology book. In case you have no idea what I’m talking about, here are again the 9 rules in short form (or your can study them in detail in the book):

1. One level of indentation per method
2. No else keyword
3. Wrap all primitives and strings
4. Use only one dot per line
5. Don’t abbreviate names but keep them short
6. Keep all entities small
7. No more than two instance variables per class
8. Use first-class collections
9. Don’t use any getters/setters or properties

Following the rules supposedly leads to more object-oriented code with a special emphasis on encapsulation. In his article, Jeff Bay suggests to do a new 1000 lines project and to follow the rules excessively without thinking twice. But hey, more object-oriented code can’t be bad for existing projects, either, can it?

Not only on the first look, many of the rules seem pretty hard to follow. For example, check your projects for compatibility with rule 7. How many of your classes have more than two instance variables? That’s what I thought. And sure, some primitives and collections deserve wrapping them into an extra class (rules 3 and 8), but do you really wrap all of them? Well, neither do we.

Other rules lead directly to more readable code. If you value good code quality like we do, rules 1, 2, 5 and 6 are more or less already in the back of your head during your daily programming work.

Especially rule 1 is what you automatically aim for when you want your crap load to remain low.

What really got my attention was rule 9: “Don’t use any getters/setters or properties”. This is the “most object-oriented” rule because it targets the heart of what an object should be: a combination of data and the behavior that uses the data.

But doing a little mental code browsing through our projects, it was easy to see that this rule is not easily retrofitted into an existing code base. The fact that our code is generally well covered with automated tests and considered awesome by a number of software metrics tools does not change that, either. Which is, of course, not surprising since committing to rule 9 is a downright big architectural decision.

So despite the fact that it is difficult to virtually impossible to use the rules in our existing projects right away, Object Calisthenics were certainly very valuable as motivation to constantly improving ourselves and our code. A good example is rule 2 (“No else”) which gets even more attention from now on. And there are definitely one or two primitives and collections that get their own class during the next refactoring.