Can anyone explain these gotchas (demo <https://go.dev/play/p/g40KMK-zsNk>)?
I've tried reading articles on this [one <https://go.dev/blog/slices-intro>,
two
<https://codeburst.io/a-comprehensive-guide-to-slices-in-golang-bacebfe46669>]
but they don't go into enough detail.
*Slight gotcha #1: arr[:N] only creates a linked slice when N < len(arr)
and arr[N:] only creates a linked slice when N>0.*
E.g. `y` is linked here:
y := x[:len(x) - 1]
and here:
y := x[1:]
But not here
y := x[:len(x)]
or here:
y := x[0:]
Also AFAICT, it's impossible create a link to an empty/nil slice unless you
use pointers. And I'm not sure if it's possible to create a linked slice
that looks at all of the elements in the original without using a pointer.
I kind of understand where the Go designers were coming from since it is
probably more efficient to avoid copying all the time. Though by that
logic, I'd still think x[0:] would create a linked slice.
*Gotcha #2: Appending to a linked slice affects the original slice but not
the other way around*
E.g. if `y` is linked to `x` via `y := x[1:], then:
- appending to `y` *might* affect x (see Gotcha #3!)
- appending to `x` won't affect `y`
If there is a link, why does it not work both ways?
*Gotcha #3: Using variadic args to append to a linked slice doesn't affect
the other one*
If `y` is linked to `x` via `y := x[:len(x) - 1], then
- append(y, 1) affects x
- append(y, 1, 2) doesn't affect x
I really don't get this one.
Thanks for any insights!
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