Rob,
"Two slices sharing an array will, however, share their last element.
Here is a better test, but this is pretty magical stuff:
https://play.golang.org/p/SZgpCh9D-l"; <https://play.golang.org/p/SZgpCh9D-l>
a := []int{0, 1, 2, 3, 4, 5, 6, 7}
s := a[1:3:5]
https://play.golang.org/p/Q8I3Vein5n
Peter
On Thursday, September 7, 2017 at 4:17:59 AM UTC-4, Rob 'Commander' Pike
wrote:
>
> That test is only sufficient if the zeroth elements in the two slices
> are at the same address, which is often not true:
> https://play.golang.org/p/TH53Pxt5Do
>
> Two slices sharing an array will, however, share their last element.
> Here is a better test, but this is pretty magical stuff:
> https://play.golang.org/p/SZgpCh9D-l Note that it cannot tell whether
> the elements actually overlap, but you can do that too if you work a
> little harder - again, capacity is the key. I leave that as an
> exercise.
>
> All that aside, copying a slice to itself is not a no-op
> computationally (it will execute the copy) but the slice will not be
> modified.
>
> -rob
>
>
> On Thu, Sep 7, 2017 at 5:41 PM, <[email protected] <javascript:>> wrote:
> > Hi,
> > Just check if backing array are same before copying:
> > https://play.golang.org/p/MSqs-jRkSO
> >
> >
> > On Thursday, September 7, 2017 at 8:54:16 AM UTC+3, Deepak Jois wrote:
> >>
> >> Hi
> >>
> >> Pls look at this code: https://play.golang.org/p/QfQOo1iyp4
> >>
> >> I am copying a slice over itself. How does it work internally? Does
> >> the copy operation optimise for this, and not perform any copying in
> >> this case?
> >>
> >> I have to deal with a situation where I get a slice reference back
> >> from a function, and it is possible that it points to the same slice
> >> that I am trying to copy it into. It would be nice if the copy
> >> operation in that case is a no-op, but I don’t want to assume that is
> >> the case.
> >>
> >> Deepak
> >
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