Question

Do you use Design by Contract professionally? Is it something you have to do from the beginning of a project, or can you change gears and start to incorporate it into your software development lifecycle? What have you found to be the pros/cons of the design approach?

I came across the Design by Contract approach in a grad school course. In the academic setting, it seemed to be a pretty useful technique. But I don’t currently use Design by Contract professionally, and I don’t know any other developers that are using it. It would be good to hear about its actual usage from the SO crowd.

Answer 1

I can’t recommend it highly enough. It’s particularly nice if you have a suite that takes inline documentation contract specifications, like so:

// @returns null iff x = 0 public foo(int x) {   ... } 

and turns them into generated unit tests, like so:

public test_foo_returns_null_iff_x_equals_0() {   assertNull foo(0); } 

That way, you can actually see the tests you’re running, but they’re auto-generated. Generated tests shouldn’t be checked into source control, by the way.