Re:Code Health: Make Interfaces Hard to Misuse (2018)
by Akronymus on Monday September 07, 2020 @05:00AM
(#24397865)
Couldn't you return a tuple with the object and the useful return value though?
Re:Code Health: Make Interfaces Hard to Misuse (2018)
by Smaug123 on Monday September 07, 2020 @05:52AM
(#24398171)
Sure - that's not the difficult part, in my book. (I use F#, where there's tuple destructuring syntax, so it's easy.) The hard parts are about making sure you can't reuse the token in the wrong context.
However, the general mindset is one I use all the time. For example, if I've written a state machine that is represented explicitly in the types, I might be able to encode some of the state transitions in the type system directly, so the compiler prevents me writing certain invalid transitions. For example, if state B can only be reached after state A, I might write the in-memory representation of B to contain an in-memory representation of A; this guarantees I must have passed something through state A to get anything in state B. Doesn't save you from everything - in particular it doesn't solve your "passing the token to the wrong instance of the object" problem - but any constraint on the state space is useful in my book. When the state machine gets sufficiently large, in my experience, the benefits of the restricted state space start outweighing the negatives of manual token shuffling.
(I have a blog post brewing about this general class of techniques, but I don't know when it'll be ready.)