Thanks all for your input, I realize now this is still somewhat of a gray area. What I ended up doing was just adding a couple convert methods, and a promotion rule. It's a relatively simple type, so that was sufficient for my purposes. The tip to use a parametric type for Arrays was particularly helpful.
On Tuesday, March 17, 2015 at 7:03:44 AM UTC-4, Kristoffer Carlsson wrote: > > This is something I thought a lot about recently. Basically, I want to > have the exact functionality of a concrete type and be able to call all > function that takes the type but I also want to be able to dispatch > differently if I want. And I don't want to manually have to copy all the > methods. > > In summary, dispatch on typealias. > > I see this has been discussed before: > > https://groups.google.com/forum/#!msg/julia-dev/v8B1tI_NB5E/tk98D0iKopYJ > > https://github.com/JuliaLang/julia/pull/3292 > > I realize this is basically subtyping from a concrete type which seems to > be a big nono but there would be so much nice things you could do with this. > > On Tuesday, March 17, 2015 at 11:02:17 AM UTC+1, Mauro wrote: >> >> > My thinking being that this would help avoid ambiguity with my code, >> as I >> > sometimes work with other units of time (e.g. seconds) that are also >> > floating point numbers. Of course, this introduced a number of problems >> in >> > my existing code, including >> >> There is also the Units.jl package, which may be of use? >> >> > 1. Arithmetic operators not defined for type JDate. My workaround >> for >> > this has thus far been to overload the operators to accept JDate >> types. >> > 2. My functions not having methods that accept time as a JDate type. >> My >> > workaround for this has been to change the function to accept >> time::FloatingPoint >> > instead of time::Float64, but this workaround does not work for >> Arrays. >> >> This is a only partially solved problem, as far as I know. How do I >> wrap a datatype without having to re-implement all its methods. >> Sometimes this can be done through subtyping, but not always. >> >> One approach is to use a macro to delegate methods to one of the fields >> of the datatype: >> >> https://github.com/JuliaLang/DataStructures.jl/search?utf8=%E2%9C%93&q=delegate >> >> https://github.com/JuliaLang/julia/pull/3292 >> >> For relatively simple number types, as in your case here, it might be >> better to manually hook into the "conversion and promotion" framework of >> Julia: >> http://docs.julialang.org/en/latest/manual/conversion-and-promotion/ >> >
