Rust Result Question Mark. Later in the read_username_from_file function another operation that returns a Result is called. In order for that character to exist inside a path it needs to be encoded differently.
Result would use FnOnce since it is just run once whereas an iterator would need FnMut since the closure would be executed once for each item. Operator can be used to make things pretty again. For example a.
On something that doesnt support the question mark operator and this can happen in a function that does have a return type that supports a question mark.
The Result type has many helper methods defined on it to do various tasks. Result would use FnOnce since it is just run once whereas an iterator would need FnMut since the closure would be executed once for each item. If it was an Err it returns from the function youre currently in. Posted on September 3 2019 by delta.