What is the difference between

[mossy axle]

Option<&String> and &Option<String>

How is it managed under memory ?

Also whats the difference between &String and &str

[solid sage]

Memory-wise, the former is a nullable pointer that points to (non-null ptr, len, capacity)

while the latter is a non-null pointer that points to (nullable ptr, len capacity)

Basically, Option<&String> is what you want most of the time

Because &Option<String> can be trivially converted to Option<&String>

using .as_ref() (https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.as_ref)

extra tip: use .as_deref() to go &Option<String> → Option<&str>

anyway

the other way around is not possible

[solid sage]

&String goes through another level of indirection

it’s less useful, you basically never want it

&str is more flexible, since it can point to:
• part of a String rather than the entire thing
• A string literal instead
• a string allocated somewhere other than the heap