qf!

API reference on docs.rs: qf!.

qf! recursively qualifies common unqualified standard-library types. It is mainly useful in generated code, where relying on imports from the caller would be impolite.

type Messages = qf!(Option<Vec<String>>);

let messages: Messages = Some(vec![String::from("hello")]);
assert_eq!(messages.as_ref().map(Vec::len), Some(1));

type Messages = ::core::option::Option<
    ::std::vec::Vec<::std::string::String>,
>;

let messages: Messages = Some(vec![String::from("hello")]);
assert_eq!(messages.as_ref().map(Vec::len), Some(1));

The recognized names are:

• String, Box, and Vec;
• HashMap, HashSet, BTreeMap, and BTreeSet;
• Option and Arc.

Only single-segment paths are rewritten. A deliberately qualified path such as application::String is preserved, because writing the qualifier is how the caller says that this is not std::string::String.