Make the Invisible More Visible

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Many aspects of invisibility are rightly lauded as software principles to uphold. Our terminology is rich in invisibility metaphors; mechanism transparency and information hiding to name but two. Software and the process of developing it can be, to paraphrase Douglas Adams, "mostly invisible".

  • Source code has no innate presence, no innate behaviour, and doesn't obey the laws of physics. It's visible when you load it into an editor, but close the editor and it's gone. Think about it too long and, like the tree falling down with no one to hear it, you start to wonder if it exists at all.
  • A running application has presence and behaviour, but reveals nothing of the source code it was built from. The number of pixels Google's home page lights up is pleasingly minimal - the goings on behind the pixels are surely substantial.
  • Lack of visible management is synonymous with lack of management. If your project is apparantly on track and one week later it's six months late you have problems, the biggest of which is probably not that it's six months late, but the invisibility force fields powerful enough to hide six months of lateness!
  • Lack of visible progress is synonymous with lack of progress. If you're 90% done and endlessly stuck trying to debug your way through the last 10% then you're not 90% done are you. Fixing bugs is not making progress. You aren't paid to debug. Debugging is waste. It's good to make waste more visible so you can see it for what it is and start thinking about trying not to create it in the first place.

Invisibility is dangerous. You manage things better when you can see them and see them constantly changing. Your thoughts are clearer when you have something concrete to tie your thinking to.

  • Writing unit tests provides evidence about how easy the code unit is to unit test. It helps reveal the presence (or absence) of developmental qualities you'd like the code to exhibit; qualities such as low coupling and high cohesion.
  • Running unit tests provides evidence about the code's behaviour. It helps reveal the presence (or absence) runtime qualities you'd like the application to exhibit; qualities such as robustness and correctness.
  • Doing iterative development increases the visibility of development progress (or lack of it) by increasing the frequency of development progress evidence.
  • Doing incremental development increases the visibility of project progress (or lack of it) by increasing the frequency of project progress evidence.

Faith is belief without evidence. I don't recommend faith based development. It's better to develop software with plenty of regular visible evidence. Visibility gives confidence that progress is genuine and not an illusion, deliberate and not unintentional, repeatable and not accidental.


By Jon Jagger

This work is licensed under a Creative Commons Attribution 3

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