Make the Invisible More Visible
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 is, to paraphrase Douglas Adams, "mostly invisible".
- Source code has no innate presence and doesn't obey the laws of physics. It's visible when loaded 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.
- By itself, source code has no behaviour. The application it specifies has behaviour, but when the application runs it reveals very little of the source code it came from. The goings on at Google are surely substantial but probably not in proportion to the pleasingly minimal number of pixels its home page lights up.
- Lack of visibility is often synonymous with lack of management. Everything is apparantly on track and one week later it's 6 months late! That would be impressive if it was true but of course it's not. It was 6 months late last week too but the invisibility field was still holding on last week.
Invisibility is dangerous. We manage things better when we can see them and see them changing. Our thoughts are clearer when we have something concrete to tie our thinking to. All useful practices have a core technical purpose, but the really useful ones also make the invisible more visible. They give confidence that progress is genuine and not an illusion, deliberate and not unintentional, repeatable and not accidental.
- Writing unit tests provides evidence about how easy the code unit is to unit test. It helps to reveal the absence of developmental qualities we'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 to reveal the absence of runtime qualities we'd like the application to exhibit; qualities such as robustness and correctness.
- Automated build
Faith is belief without evidence. I don't recommend faith based development. It's better to develop software with plenty of regular visible evidence.
By Jon Jagger
This work is licensed under a Creative Commons Attribution 3
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