Right now, to insert a new value into a std::collections::HashMap, one must transfer ownership of the key to the map. The map however does not seem to require ownership of the key.
The HashMap does not keep around a copy of the key however. It only stores its hash. This means that there is no way to get the key out of the HashMap again.
For example, take the signature of the insert method:
fn insert(&mut self, k: K, v: V) -> Option<V>
If the value is updated, it returns the old value, thus giving the user ownership of said value again. The key however, is lost forever. There is no way to get it back.
Right now, to insert a new value into a
std::collections::HashMap, one must transfer ownership of the key to the map. The map however does not seem to require ownership of the key.The
HashMapdoes not keep around a copy of the key however. It only stores its hash. This means that there is no way to get the key out of theHashMapagain.For example, take the signature of the insert method:
If the value is updated, it returns the old value, thus giving the user ownership of said value again. The key however, is lost forever. There is no way to get it back.