Ian, can you clarify that for me, so the GC tracks interior pointers (to a
slice of structs) so that even if there are no references to the outer slice it
will not be GCd? That would seem to be very expensive.
> On Nov 9, 2019, at 9:36 AM, sirp...@gmail.com wrote:
>
>
> Thanks for these responses.
>
>> On Tuesday, 6 August 2013 22:06:38 UTC+1, Ian Lance Taylor wrote:
>> On Tue, Aug 6, 2013 at 1:57 PM, Jakob Borg <ja...@nym.se> wrote:
>> > 2013/8/6 Ian Lance Taylor <i...@golang.org>:
>> >> It is designed that way because we want to permit setting a new key in
>> >> a map to grow the hash table if necessary, moving the map around in
>> >> memory. That means that the language can not permit taking the
>> >> address of an entry in a map--if it could, it would not be possible to
>> >> move a map in memory.
>> >
>> > How come append to a slice doesn't ever need to move the contents in
>> > order to grow the slice?
>>
>> When append needs to move the contents, it gives you a slice that
>> refers to a new backing store. The old backing store still exists and
>> pointers to it are still valid. And a program could even reasonable
>> use it.
>>
>> This does mean that whether a function like this prints 2 or 100
>> depends on the details of the implementation of append.
>>
>> func main() {
>> a := append([]int{}, 1, 2, 3)
>> a = append(a, 4)
>> p := &a[1]
>> a = append(a, 5, 6, 7)
>> a[1] = 100
>> fmt.Println(*p)
>> }
>>
>> Ian
>
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