The Seven States of a Boolean Object

Everyone understands Boolean variables – they’re either true or they’re false. Right? Except, in languages, where the Boolean variable might be null, which makes comparing two Boolean values a little little trickier. And the DailyWTF once gave an example of a Boolean ENUM that could be true, false or file-not-found.

Long ago, when I worked for Tom Hume at Future Platforms, one of the developers suggested something more ambitious. After all, a three-state Boolean leaves too much room for ambiguity. By the time he was done, Thom Hopper had suggested 6 or 7 states for a Boolean variable. Tom Hume and I recently tried to remember as many as we could, but only got 5 or 6.

We tweeted Thom Hopper to see if he remembered, but the states of this variable are lost in time, like tears in rain. But, for the sake of posterity, I want to record some of the values that a proper Boolean type might hold:

• true
• false (obviously)
• null
• uninitialised (similar null – but this means a true/false has never been set)
• unknown (we’re currently not certain of the value)
• indeterminate (there’s no way of knowing this value)

I’ve love to be able to declare that this is stupid, but I don’t know. I mean, if you accept null as a Boolean state, where do you stop? Maybe Java needs a ‘true’ boolean that can take all of these states?

Living Without Pre-Production Environments

Would we be better off without test environments?

I try not to recommend too many talks, but I loved this one from Nicky Wrightson of Skyscanner about living without pre-production environments. It provides an interesting solution to a lot of problems with performance environments I’ve been thinking through. Trying to accurately reproduce live environments seems like a wasteful, quixotic endeavour and I kept wondering about was just not using them. This video is an encouragement to that thinking.

Talks are often very different to the reality in companies, but there are some great questions for anyone about what test environments are for. “Historically, we had lower environments that were like production so that we could test releases that we couldn’t confidently reason about the effect of the changes.”

The only performance test that actually matters is how the live environment. ”At the end of the day, just make it a lot easier to track issues in production with really well instrumented code rather than try to replicate those issues in lower environments”.

There will always be inherent differences between environments, which limits the ability to draw conclusions from them. Yes, H2 is great for integration testing, but it has subtle differences with Oracle and MySQL which need managing. In performance tests, replicating load is hard – data and traffic shapes are as important as infrastructure and code. And then there are all the environment specific configs to manage, and the bugs from that.

Obviously, doing away with testing environments is the sort of decision that gets people fired. But! Just imagine how much things would improve if it worked!