zlacker

>>signa1+(OP)
I feel like I’m taking crazy pills. How are these APIs even remotely defensible?

    slices.Sort(s)          // fine
    slices.Compact(s)       // broken
    s  = slices.Compact(s)  // fine
    s := slices.Compact(s)  // broken (!!!)
    slices.Delete(s, …)     // broken
    s = slices.Delete(s, …) // fine

How is one intended to remember which functions require overwriting (due to invalidating) their input and which don’t? Why does the language make it so easy to render function parameters unusable upon return but impossible to enforce that they aren’t used afterward?

How on earth did it take twelve years for this “simple” language to make a function to delete elements from an array, with `s = append(s[:start], s[end:]...)` having to suffice until then? How on earth does the “better” API twelve years later have such a gaping footgun? This is a core type that quite literally every program uses. How have things gone so far off the rails that “setting the obsolete pointers to nil” is such an intractable problem for end users they had to add a new keyword to the language?

For other languages I see posts where weird language corner cases bring up challenging issues that really reinforce the idea that language design is hard. Rust—for example—has unsoundness issues in corner cases of the type system. But for go, it feels like there’s a constant stream of own goals on core areas of the language where the design should have knocked it out of the park. “Simple manipulation of arrays” just should not have this many footguns.

>>stouse+9l3
Without defending this API, the easiest way to go about avoiding bugs when working with slice mutating functions is to consider all those "fine" scenarios as not fine.

Always assume that only the return value of slice mutating functions are the valid reference and the old one always invalid. This is not always completely accurate, but it is very useful in that, it is also never "wrong".

>>omeid2+hm3
> Without defending this API, the easiest way to go about avoiding bugs when working with slice mutating functions is to consider all those "fine" scenarios as not fine. Always assume that only the return value of slice mutating functions are the valid reference and the old one always invalid.

The first "fine" scenario is fine because `slices.Sort` works in place, it doesn't return a value at all.

And the other "fine" versions do essentially what you advocate, by overwriting the invalid reference with the new one.

>>maskli+op3
By returning nil, the function makes it clear that it doesn't move the input reference