On Friday, March 3, 2017 at 10:32:25 PM UTC+8, Ian Lance Taylor wrote:
>
> On Fri, Mar 3, 2017 at 5:31 AM, T L <tapi...@gmail.com <javascript:>>
> wrote:
> >
> > On Friday, March 3, 2017 at 7:52:42 PM UTC+8, Ian Davis wrote:
> >>
> >> Perhaps you can help the discussion by explaining the advantages you
> see
> >> in that change?
> >
> >
> > The advantage is to save a few bytes memory and make faster copying.
>
> I don't see how the suggestion saves memory. Currently, we can
> represent a string or slice with a single allocation. Your suggestion
> would require us to use two allocations: one for the bytes, and one
> for the structure pointing to the bytes. In some cases escape
> analysis would eliminate that second allocation, but not in all.
>
> Ian
>
>
Yes, the suggestion needs more allocations in creating new string and slice
values.
But it makes copying string and slice values a little faster and a little
less memory consuming.
>
> >> On Fri, 3 Mar 2017, at 11:44 AM, T L wrote:
> >>
> >>
> >>
> >> On Friday, March 3, 2017 at 4:27:02 PM UTC+8, Konstantin Khomoutov
> wrote:
> >>
> >> On Thu, 2 Mar 2017 23:49:52 -0800 (PST)
> >> T L <tapi...@gmail.com> wrote:
> >>
> >> > After all, the len and cap fields of any value of string and slice
> >> > values are immutable.
> >>
> >> Could you elaborate?
> >>
> >> Are you suggesting to replace
> >>
> >> var s []string
> >>
> >> if len(s) ...
> >> if cap(s) ...
> >>
> >> with
> >>
> >> if s.len ...
> >> if s.cap ...
> >>
> >> ?
> >>
> >> If yes, then what would be the prospective benefits?
> >>
> >>
> >>
> >> No, I mean why not define string and slice as
> >>
> >> type string struct {
> >> underlyingString *struct {
> >> data *byte
> >> len int
> >> }
> >> }
> >>
> >> type slice struct {
> >> underlyingSlice *struct {
> >> underlyingElements unsafe.Pointer
> >> len int
> >> cap int
> >> }
> >> }
> >> instead of the current:
> >>
> >> type string struct {
> >> data *byte
> >> len int
> >> }
> >>
> >> type slice struct {
> >> underlyingElements unsafe.Pointer
> >> len int
> >> cap int
> >> }
> >>
> >>
> >>
> >>
> >>
> >> --
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> >>
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