On Wed, Oct 7, 2020 at 9:12 PM Howard C. Shaw III <howardcs...@gmail.com>
wrote:
> You said:
>
>> I was trying around with arrays and generics because slices are more
>> complex to reason about than arrays. For example, I introduced bugs into my
>> code by not being fully aware of slices overwriting original data when you
>> append to them and the capacity is not set correctly. So, when writing
>> critical code it could be safer to avoid slices if possible for
>> this reason. Another example:
>>
>
> In my experience, you either have a fixed array size in mind to begin with
> (as in a fixed array size in a struct for padding or matching a fixed size
> C array) or you should be using a slice anyway.
>
> The trouble mostly comes when you keep the array around after making a
> slice of it. If you are going to be doing *any* manipulation of a slice,
> abandoning the underlying array and only carrying around slices gets rid of
> most such errors. A slice already IS effectively an 'array, generic on
> size.'
>
Hm, abandoning the underlying array does not really help I think:
u := []byte{0, 1, 2, 3}
a := u[0:2]
b := u[2:]
u = nil // abandon u
a = append(a, 4)
fmt.Println(b) // [4, 3]!! not intended
Should be:
u := []byte{0, 1, 2, 3}
a := u[0:2:2] // use correct capacity!
b := u[2:len(u)] // use correct capacity!
u = nil // abandon u
a = append(a, 4)
fmt.Println(b) // [2, 3], ok!
Btw, I am not saying fixed arrays are a solution for this of course and I
agree it is not a big problem in practice as otherwise slices are really
handy.
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