OOPSLA Day 2: Explicit Use-Case Representation in Programming Languages

One of the emerging themes at this conference is the need to move “examples” (and their older siblings, scenarios and use-cases) “into the code,” so that examples/stories/scenarios/use-cases, which are tremendously meaningful to the subject-matter experts, are actually traceable directly into the code, which is tremendously meaningful to, you know, the machine.

I very much enjoyed a talk on “Use-case Representation in Programming Languages,” which described a system called UseCasePy that added a @usecase annotation to Python methods. So you would have:
[sourcecode]
@usecase(DrawARectangle,DrawALine)
def drawLine(ptA, ptB) … etc …
[/sourcecode]

Now, even if you go no further, you’re doing better than something in a documentation comment, since you can easily write a tool that iterates over all source-code, queries the metadata and builds a database of what classes and methods participate in every use-case: very useful.

Even better, if you have a runtime with a decent interception hook, you can run the program in a particular use-case (perhaps from your BDD test suite, perhaps from an interactive tool), acquire the set of methods involved, and determine, by exercising a large suite of use-cases, metrics that relate the codes “popularity” to user-meaningful use-cases, which could be very helpful in, for instance, prioritizing bug-fixes.

Oh, by the way, apparently we no longer call them “users” or even “domain experts,” they are now “Subject Matter Experts” or even SMEs (“Smees”).