Thanks, that makes more sense! In my case I wanted `Name1{S} <: S` but
neither `Name1 <: S` or `S <: Name1` make sense.
On Saturday, April 2, 2016 at 12:47:07 PM UTC-7, Erik Schnetter wrote:
>
> Julia's type hierarchies use single inheritance only. Thus inheritance
> mechanisms that work fine in C++ can't always be made to work in
> Julia. There are discussions on introducing concepts (traits), but
> that's still in a prototype stage. (I'm using traits
> <https://github.com/mauro3/Traits.jl> in a project of mine; this works
> fine, only the error messages are sometimes confusing.)
>
> If you have `Name1{S <: Name2} <: S`, and you need to stick with
> single inheritance, then you essentially define both
>
> `Name1{S} <: Name1
> `Name1{S} <: S`
>
> (here `Name1` is the abstract type that Julia introduces for every
> parameterized type; `Name1` is different from `Name1{S}`).
>
> Since Julia uses single inheritance, you also need to have either
> `Name1 <: S` or `S <: Name1`. Both would be strange, since they would
> introduce a relation between `Name1` and `S`, but you haven't
> specified `S`.
>
> -erik
>
>
> On Sat, Apr 2, 2016 at 3:36 PM, Scott Lundberg <[email protected]
> <javascript:>> wrote:
> > Thanks Erik, though I am not quite clear how it would break things.
> >
> > As for the real goal:
> >
> > Name2 is also templated such as Name2{A} and Name2{B}. There are lots of
> > methods that dispatch depending on Name2{A} or Name2{B}.
> >
> > I want to add a subtype of Name2 (which I call Name1) that still
> correctly
> > dispatches for those methods. Another way I would like to do it is:
> >
> > abstract Name1{Name2{T <: AvsB} <: Name2{T}
> >
> > but of course that also does not work.
> >
> > Thanks!
> >
> > On Saturday, April 2, 2016 at 11:55:47 AM UTC-7, Erik Schnetter wrote:
> >>
> >> If you define an abstract type `Name1{S}`, then Julia automatically
> >> defines another abstract type `Name` with `Name1{S} <: Name`.
> >>
> >> This would break if you tried to insert `S` into the type hierarchy as
> >> well.
> >>
> >> -erik
> >>
> >> On Sat, Apr 2, 2016 at 2:51 PM, Tomas Lycken <[email protected]>
> wrote:
> >> > If it's abstract, what is the purpose of the type parameter? In other
> >> > words,
> >> > what is the ultimate goal you're reaching for?
> >> >
> >> > //T
> >> >
> >> > On Saturday, April 2, 2016 at 3:17:34 AM UTC+2, Scott Lundberg wrote:
> >> >>
> >> >> You can define:
> >> >>
> >> >> abstract Name1{S <: Name2} <: Name3{S}
> >> >>
> >> >> but I want to define:
> >> >>
> >> >> abstract Name1{S <: Name2} <: S
> >> >>
> >> >> However the second line does not work. Is there some other way to
> >> >> accomplish the same thing? Thanks!
> >>
> >>
> >>
> >> --
> >> Erik Schnetter <[email protected]>
> >> http://www.perimeterinstitute.ca/personal/eschnetter/
>
>
>
> --
> Erik Schnetter <[email protected] <javascript:>>
> http://www.perimeterinstitute.ca/personal/eschnetter/
>
