undefined | Better HN

0 pointspreseinger2y ago0 comments

given a function fn that can fail, it will return a result and an error e.g.

    result, error = fn(...)

calling this function should yield to the caller two possibilities, somehow: a success value _or_ a failure error

the important thing is that in both cases, the control flow is visible in the source code as written

    result, error = fn(...)
    if there was an error, ...
    if it was successful, ...

when an expression fails, you want to see the consequence in-line

the success path and the failure path are equally important

0 comments

za3faran2y ago

Nothing is preventing the code from returning both at the same time. I've seen code (including in the standard library) that returns both an error and a return value. In a language with disjoint unions, such cases would be encoded properly.

preseingerOP2y ago

convention prevents it

and in the case where returning both is OK, then documentation makes that clear

this is not difficult

aniforprez2y ago

Convention in no way prevents anything. Convention is simply that. People are free to not follow convention when nothing is enforcing it. You frequently see juniors, who may be brand new to the language, making mistakes with conventions. If I'm supposed to depend on the vagaries of some accepted standard that is only documented in text then it is less than useless in the real world

1 more reply

za3faran2y ago

We all know that documentation always 100% matches the behavior of the code :-)

andrewjf2y ago

Yeah, but you're still relying on the programmer to do it correctly which is nothing but false hope.

preseingerOP2y ago

no, it isn't

j / k navigate · click thread line to collapse