On Tue, Oct 30, 2018 at 6:13 AM, Jamie Clarkson <jamiec7...@gmail.com> wrote:
>
> Apologies if this is covered somewhere, have searched and not found.
>
> I'm curious about the Go2 generics draft, how does the team envisage the
> code generated for the ShortestPath (without code expansion like C++
> templates where it's obvious)? I can come up with two so far.
>
> i) Use reflect to look up method names:
>
> So the basic generic ShortestPath would look a bit like:
>
> func ShortestPath(src,dst interface{}) interface{} {
> srcV := reflect.ValueOf(src)
> edgesM := srcV.MethodByName("Edges")
> edges := edgesM.Call(...)
> // etc.
> }
>
> ii) Autogenerate mutually recursive interfaces:
>
> type _N interface {
> Edges() []_E
> }
>
> type _E interface {
> Nodes() []_N
> }
>
> func ShortestPath(src,dst _N) []_N {
> edges := src.Edges()
> // etc.
> }
>
> I'm not considering the problems with either approach, like having to wrap
> the actual concrete types or conversions of slice values.
>
> I'm also guessing I'm missing something obvious that makes it easy.
None of this has been implemented, so it's impossible to be sure.
That said, one approach is for the compiler to create implicit
interface types not only for Node and Edge but also for []Node and
[]Edge. The implicit interface created for the slice types will
handle the slice indexing. The usual steps for conversion of
non-interface types to interface types will handle the method results.
Writing this out is left as an exercise for the reader.
Ian
--
You received this message because you are subscribed to the Google Groups
"golang-nuts" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to golang-nuts+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
