Setting the slice to nil is the best way to clear a slice. nil slices in go are perfectly well behaved and setting the slice to nil will release the underlying memory to the garbage collector.
package main
import (
"fmt"
)
func dump(letters []string) {
fmt.Println("letters = ", letters)
fmt.Println(cap(letters))
fmt.Println(len(letters))
for i := range letters {
fmt.Println(i, letters[i])
}
}
func main() {
letters := []string{"a", "b", "c", "d"}
dump(letters)
// clear the slice
letters = nil
dump(letters)
// add stuff back to it
letters = append(letters, "e")
dump(letters)
}
Prints
letters = [a b c d]
4
4
0 a
1 b
2 c
3 d
letters = []
0
0
letters = [e]
1
1
0 e
Note that slices can easily be aliased so that two slices point to the same underlying memory. The setting to nil will remove that aliasing.
This method changes the capacity to zero though.