How do I design a class in Python?

Question

I\'ve had some really awesome help on my previous questions for detecting paws and toes within a paw, but all these solutions only work for one measurement at a time.

No

Answer 1

I like the TDD approach... So start by writing tests for what you want the behaviour to be. And write code that passes. At this point, don't worry too much about design, just get a test suite and software that passes. Don't worry if you end up with a single big ugly class, with complex methods.

Sometimes, during this initial process, you'll find a behaviour that is hard to test and needs to be decomposed, just for testability. This may be a hint that a separate class is warranted.

Then the fun part... refactoring. After you have working software you can see the complex pieces. Often little pockets of behaviour will become apparent, suggesting a new class, but if not, just look for ways to simplify the code. Extract service objects and value objects. Simplify your methods.

If you're using git properly (you are using git, aren't you?), you can very quickly experiment with some particular decomposition during refactoring, and then abandon it and revert back if it doesn't simplify things.

By writing tested working code first you should gain an intimate insight into the problem domain that you couldn't easily get with the design-first approach. Writing tests and code push you past that "where do I begin" paralysis.