SetMapIndex() equivalent for slice/array

[Deiter]

The reflect package provides the SetMapIndex method for updating elements in a map that are represented by a reflect.Value type, but I don’t see an equivalent for array/slice.

The sample app (link provided below) includes an example of map that’s been made accessible through a a reflect.Value type variable. One of the elements in the map is updated using SetMapIndex.

The sample app also includes an example of a slice containing exactly the same data as the map. As far as I can tell, the only way to update an element of the slice through a reflect.Value type variable is to introduce unsafe package

Is there a better way that I’m missing that doesn’t require the use of the unsafe package

SetMapIndex() equivalent for slice/array

[Kurtis Rader]

More context would be useful; i.e., what are you really trying to do and why? Such information often allows people to provide better answers; including whether this is an example of the [XY Problem](https://xyproblem.info/) or you have a misunderstanding how slices work. Given your play.golang.org reproducer neither of those responsies seem likely but nonetheless...

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Kurtis Rader

Caretaker of the exceptional canines Junior and Hank

[Howard Waterfall]

I'm trying to decouple algorithm from type. if an algorithm works on a collection, it ought to work on either a map or slice. It appeared that result.Value facilitated the decoupling entirely, until I ran into the limitation with array/slice. It seems odd that I have to use the unsafe the package with array/slice esp. given the support provided for maps with SetMapIndex. I figure I must be missing something…

[Dan Kortschak]

You can call Set on the reflect.Value returned by Index of a slice or
array.

slice: https://play.golang.org/p/b1NscgQ7UC5
array: https://play.golang.org/p/xCAGuTL5Wbl

[Howard Waterfall]

Dammit!. How'd I miss that?! Thanks Dan. I updated the sample accordingly.

[Howard Waterfall]

Updated sample