Thanks, Ian.
On Sunday, April 12, 2020 at 9:10:25 PM UTC-7, Ian Lance Taylor wrote:
>
> On Sun, Apr 12, 2020 at 8:28 PM Ram Kumar <forwar...@gmail.com
> <javascript:>> wrote:
> >
> > Documentation for "container/heap" says
> >
> > Package heap provides heap operations for any type that implements
> heap.Interface.
> >
> > heap.Interface is
> >
> > type Interface interface {
> > sort.Interface
> > Push(x interface{}) // add x as element Len()
> > Pop() interface{} // remove and return element Len() - 1.
> > }
> >
> > The example program provided in the documentation has these methods
> >
> > // An IntHeap is a min-heap of ints.
> > type IntHeap []int
> >
> > func (h IntHeap) Len() int { return len(h) }
> > func (h IntHeap) Less(i, j int) bool { return h[i] < h[j] }
> > func (h IntHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
> >
> > func (h *IntHeap) Push(x interface{}) {
> > // Push and Pop use pointer receivers because they modify the slice's
> length,
> > // not just its contents.
> > *h = append(*h, x.(int))
> > }
> >
> > func (h *IntHeap) Pop() interface{} {
> > old := *h
> > n := len(old)
> > x := old[n-1]
> > *h = old[0 : n-1]
> > return x
> > }
> >
> > heap.Push() and Pop() are implemented by *IntHeap and the sort.Interface
> is implemented by IntHeap. In other words heap.Interface is not implemented
> by one single type.
> >
> > Doesn't this violate the requirement "Package heap provides heap
> operations for any type that implements heap.Interface." ? Appreciate any
> help to understand this better.
>
> All methods of intHeap are also methods of *intHeap (see
> https://golang.org/ref/spec#Method_sets). So the type *intHeap
> implements heap.Interface.
>
> Ian
>
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