[flagged]
The worst are methods that both mutate and return values. I know this gets into a complex land of computer science that I don’t understand well, but I wish I could define in TypeScript “any object passed into this function is now typed _never_. You’ve destroyed it and can’t use it after this.” Because I sometimes want to mutate something in a function and return it for convenience and performance reasons, but I want…
ruby has the convention of ! for dangerous destructive or mutating methods. This is something that I wish would spread around a bit.
For example:
# Original array
array = [1, 2, 3]
# Using map (non-destructive)
new_array = array.map { |x| x * 2 }
# new_array is [2, 4, 6]
# array is still [1, 2, 3] (unchanged)
# Using map! (destructive)
array.map! { |x| x * 2 }
# array is now [2, 4, 6] (modified in-place)