On Friday, August 16, 2024 10:37:45 AM MDT Nick Treleaven via Digitalmars-d- learn wrote: > On Friday, 16 August 2024 at 16:30:09 UTC, Jonathan M Davis wrote: > > Whether the result of dup is then able to be implicitly > > converted to immutable based on whether the operation is pure > > depends on the element type and where the result is used. > > If it can't be converted to immutable then `idup` won't work > either.
Yes, but if you use idup, then the result is always immutable, whereas if you use dup, it's mutable unless it's used in a context where it has to be immutable. So, in the general case, you need to use idup if you want to be sure that you get immutable. You can still get immutable in specific cases, but there will be plenty of cases where you won't, and even if you do right now, that could change when refactoring. Something as simple as a function being changed from taking string to taking a range of characters could then change the type that you get. So, it's probably better practice to just always use idup when you want immutable, but obviously, developers can choose to do otherwise and make it work just fine so long as they're consistently using the result of dup in a context which requires immutable. - Jonathan M Davis
