HashMap.get() dereferenced

help
1

What is the idiomatic way to get a dereferenced copy (in case of Copy trait) of a value from a hashmap or other collection that returns a Option<&Value> where Value: Copy?

Do I have to match

match collection.get(key) {
  None => None,
  Some(v) => Some(*v),
}

or is there a nicer way?

2

The recently stabilized Option::copied

3 Likes
3

For a non-Copy type, do Option::copied() and Option::cloned() have identical performance?

4

Option::copied requires T: Copy, because ... well, you can't copy non-copy types.

for Copy types clone and copy are identical.

5

Not always, for example in generic code you may see differences.

6

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