Return top-level keys from map using generic type parameters

Question content

I have the following method which returns all keys in map. But the parameters it accepts must be of type map[string]string.

func GetAllKeys(m map[string]string) []string {
    keys := make([]string, len(m))
    i := 0
    for k := range m {
        keys[i] = k
        i++
    }

    return keys
}

How do I reuse this method if I have a map but of type map[string]map[string]string. Is there a way to generalize this method since all it would do is return the top level key from the map.

Correct answer

With go 1.18 you can use Type parameters:

func GetAllKeys[K comparable, V any](m map[K]V) []K {
    keys := make([]K, len(m))
    i := 0
    for k := range m {
        keys[i] = k
        i++
    }
    return keys
}

https://www.php.cn/link/3eb46aa5d93b7a5939616af91addfa88

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