On Saturday, March 4, 2017 at 12:47:10 AM UTC+8, T L wrote:
>
>
>
> 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> 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.
>
>
And yes, avoid one more memory allocation is a good reason to reject the
suggestion. :)
>
>
>>
>> >> 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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