> I’ve been told to default to pass-by-reference in the past because most traits take &self and not self This is only blanket advice for designing traits, beca

> I’ve been told to default to pass-by-reference in the past because most traits take &self and not self This is only blanket advice for designing traits, because as the trait author you don't know what concrete type the downstream user is going to want to use, and taking `&self` in that circumstance is the choice that is friendliest to both Copy and non-Copy types. If you're just writing a non-generic function and you do know what concrete types you're using, the flowchart is pretty simple: 1. If the type is not Copy, then pass by-ref if you just need to read the value, pass by-mutable-ref if you just need to mutate the value, and pass by-value if you want to consume the value. 2. If the type is Copy, then pass by-value, but if your type is really big or if benchmarking has determined that this is a critical code path then pass by-ref.