This happens only because z is copied every time, but has nothing to do
with interfaces. This exhibits the same behavior without
interface{}: https://play.golang.org/p/C5KoUST4Zn
You could in fact modify the slice's existing content, but not the slice
itself. For example:
x := make([]int, 1, 5) // we have 1 element
x[0] = 42
for i := 0; i < 4; i++ {
z := x
z[0] = z[0] + 1
z = append(z, i))
}
fmt.Println(x[0]) // would print 46
fmt.Println(len(x) // still 1
Well, unless you move z's declaration out of the loop as Jan suggested.
I'd recommend reading https://blog.golang.org/go-slices-usage-and-internals
(manipulating slice values was not obvious to me until I read this).
Le jeudi 2 mars 2017 15:23:21 UTC+1, James Bardin a écrit :
>
> All assignments are a copy, so there's no way to modify a slice value that
> is in an interface{}
>
> Just like if this were a function argument, you will need a pointer in
> order to modify the value.
> https://play.golang.org/p/kOdXUCiT_F
>
>
>
> On Thursday, March 2, 2017 at 9:01:48 AM UTC-5, Cornel Damian wrote:
>>
>> If you look where the slice is printed you will see that the data is
>> missing. In the working example from me the data is there.
>> And even so, your example doesn't help me, what i've set there is just
>> for example, i my code each time i add data to the slice i must first cast
>> it.
>>
>> On Thursday, March 2, 2017 at 3:56:58 PM UTC+2, Jan Mercl wrote:
>>>
>>> On Thu, Mar 2, 2017 at 2:46 PM <bar...@gmail.com> wrote:
>>>
>>> > Can somebody explain me why?
>>>
>>> Did you mean https://play.golang.org/p/GUVZBUQlEj ?
>>>
>>> --
>>>
>>> -j
>>>
>>
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