Archive for April, 2014

Pronking for programmers

If you watch wildlife documentaries, you’ve probably seen pronking, or stotting—the strange four-legged jump that gazelles do:

Pronking is Afrikaans for “showing off,” and that’s certainly part of what’s going on, but it’s not quite as simple as that. Gazelles don’t only pronk to show off—they also pronk when they’re being chased by a predator. I always assumed that this was about evading the predator by being unpredictable, but it turns out that there’s a rather surprising alternative explanation.

Pronking slows the animal down and uses up energy that (you might think) would be better spent running away. But it works—animals that pronk are less likely to be caught than those that don’t. So what’s going on?

The theory is that pronking is a way for a gazelle to demonstrate that it’s fit. “Don’t bother chasing me—I’ll be too difficult to catch. Chase my cousin over there, the one with the limp—he’ll be much easier to catch.”

Pronking works because it’s expensive. If every gazelle could pronk, predators would pay no attention. But only fit gazelles can, so it’s an honest signal.

So what does this have to do with programmers? Too many pizzas and donuts mean that quite a few of us won’t be able to literally pronk, but that doesn’t stop us from doing it in our own way…

I think that we pronk when we contribute to open source.

There are lots of reasons to contribute to open source. It’s a great way to improve the tools we all rely on, give back to the community, and learn new skills. But, let’s be honest, it’s also a great way to show off and demonstrate our fitness.

And it works—when I find myself sifting through a pile of CVs, evidence of significant open source contributions is virtually guaranteed to make sure a CV doesn’t find itself on the “rejects” pile. And like pronking, it works because it’s expensive—the time and effort required is concrete evidence that the candidate cares about their craft.

So if you can pronk, perhaps you should?

ScalaMock Status Report

Apart from a little work to make it compatible with the most recent versions of Scala and ScalaTest (thanks to Chua Chee Seng, Duncan Crawford and Chris Birchall) ScalaMock has been moribund over the last 12 months. This is partly because my focus has been on writing Seven Concurrency Models in Seven Weeks, but mostly because of insurmountable issues with Scala’s current macro support.

There is good news on both fronts, however. First, I recently finished the book, so I should now have more time to devote to ScalaMock. And second, Eugene has announced Palladium, which looks like it should provide everything that ScalaMock needs.

So where is ScalaMock now? And where is it (hopefully) going?

Where is ScalaMock today?

ScalaMock 3 supports two types of mock, proxy mocks and macro mocks.

Proxy mocks are not type checked and have a slightly less convenient syntax than macro mocks, but they work with any trait and are fully supported.

Macro mocks are type checked and have a nicer syntax than proxy mocks. They work well with most traits, but fail for traits with “complex” type signatures.

The good news is that macro mocks either work or give a compile error (there should be no situations where a macro mock compiles but gives “odd” results). And if you have a trait for which macro mocks don’t work, you can always use a proxy mock instead.

Where is ScalaMock going?

As soon as Palladium is available, I plan to start working on ScalaMock 4. If Palladium delivers on its promise, ScalaMock 4 should be able to mock any trait, no matter how complex its type. In addition, I expect that it will also support:

  • Improved syntax:


    instead of:

    (mockObject.method _) expects (arguments)
  • Mocking object creation (constructors)
  • Mocking singleton and companion objects (static methods)
  • Mocking final classes and classes with final methods or private constructors