mbaz (Mar 24 2023 at 17:08): mbaz (Mar 24 2023 at 17:08):Consider a package that keeps some state consisting of objects of type Object. New objects are instantiated and given an ID with Object(ID).
Users can select a particular object. This can be done in at least two ways:
Object(ID) return the existing object if ID already exists and a new object otherwise.Object(ID) to be a true constructor, which can only create new objects, and use another function (say) object(ID) to select existing objects.Which is better? Method 2 is arguably "purer" and more elegant, since constructors are used only to construct, but it probably requires more mental effort from users ("am I constructing or am I selecting?")
Expanding Man (Mar 24 2023 at 17:21):As I recall, the Julia documentation hints that Object is expected to return a new object, but there are certainly packages around in the ecosystem that use constructors to access existing objects. I myself have occasionally used them as "getters", though if I thought more carefully about it I'd probably regret that practice (get(x, ::Type{Object}) seems better). I think option 2 is probably better.
Last updated: Nov 07 2025 at 04:42 UTC