On Fri, Oct 19, 2018 at 12:01 PM Ian Denhardt <i...@zenhack.net> wrote:
>
> Quoting Burak Serdar (2018-10-19 12:34:44)
> > Re: Ian Denhardt's proposal:
> >
> > I agree that it handles all the cases in the official proposal,
> > but I think the syntax is too verbose and reminds me of
> > Java. For instance, the "sorting" example can be written using
> > the "like" keyword as:
> >
>
> > Template:
> >
> > type orderedSlice []like (int,string)
> >
> > func (s orderedSlice) Len() int { return len(s) }
> > func (s orderedSlice) Less(i, j int) bool { return s[i]<s[j] }
> > func (s orderedSlice) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
> >
> > // There is no need for an OrderedSlice function
> >
> > Concerete use:
> >
> > type mySlice orderedSlice []int64
> >
> > v:=mySlice{1,2,3}
> > sort.Slice(v)
>
> This example in my proposal was intended to show the minimal change
> needed from the draft design, but I also mentioned that you actually
> didn't need `orderedSlice` at all to sort slices. If you combine it
> with Eric's proposal for operator overloading, you can just write
>
> v := []int64{1,2,3}
> sort.Slice(v)
>
> ..with no boilerplate type/method definitions, or casts, at all.
>
> > However, one limitation of using interfaces to specify contracts
> > is that you can't use a struct type as a basis for your
> > contract. For instance, going back to the linked list example:
> >
> > type Node like struct {
> > next *Node
> > }
> >
> > With interfaces as contracts, this becomes:
> >
> > type Node(type E) interface {
> > GetNext()
> > SetNext(*Node(E))
> > }
>
> This is true; exposing the next-pointer structure of a linked list
> through an interface is more verbose. However I'm not convinced there
> are good uses for this; Can you provide an example where such a template
> would actually be useful?
It is useful in a linked list. You can instantiate a linked list
template in a package, and use that concrete type in another package
without access to the internals of the linked list.
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