On Sun, Jul 19, 2015 at 11:44 AM, andrew cooke <and...@acooke.org> wrote: > > 1 - i asked myself the same question after posting and went back and looked > at the use case that motivated this. and it was for values that i need to > mutate early in their lifetime, and which then remain invariant. i've been > thinking about how i could have done it differently, and one approach i am > considering is re-creating the objects during the start-up process. i think > that would work. so that particular use case is perhaps not so convincing.
If I understand correctly, this is what motivate this julep[1] (the more general case) [1] https://github.com/JuliaLang/julia/issues/11902 > > 2 - however, isn't there still a case for things that should be semantically > equal, even though they are composite? maybe i am misunderstanding how > things work, but i could imagine some object that stored, say, name and age. > if i used an immutable type then equality would depend on interning of > strings, wouldn't it? another example would be immutable arrays. in short: > immutable things that are accessed by a pointer, and whose contents you want > to include in equality. > > andrew > > > On Sunday, 19 July 2015 11:53:43 UTC-3, Stefan Karpinski wrote: >> >> I don't really get what's lacking. If you want an immutable record type >> why not just use an immutable type? >> >> On Jul 19, 2015, at 8:03 AM, andrew cooke <and...@acooke.org> wrote: >> >> >> you may be interested in https://github.com/andrewcooke/AutoHashEquals.jl, >> but it uses all entries. i will consider adding that feature, though (with >> the idea that if it's not used at all, all are used). >> >> more generally - and this may just be a problem with my programming style >> - i find that there's a problem with julia (or me) conflating two different >> things: >> >> * record types >> * immutable types >> >> immutable types in julia are intended, as far as i can see, for small, >> value-like things that are stored on the stack. while "types" are for >> larger, record like things. >> >> some of us (perhaps coming more from a functional programming background) >> like to program with records that are immutable, we have no way to do that >> in julia except by convention. >> >> hence the need for AutoHashEquals (imho) (there are two problems - first, >> most obviously, you then want record equality to depend on contents, but >> second, less obviously, when these "immutable records" are used in immutable >> types then you want the immutable type's hash to depend on the record's >> contents, and not on the pointer value. hence applying the macro to both >> types). >> >> andrew >> >> >> On Friday, 17 July 2015 12:52:52 UTC-3, Seth wrote: >>> >>> Perhaps a @unique macro in front of the type field could specify that >>> this is to be used in equality/hashing? >>> >
