Exercise

1. What do these names imply they do?
2. What should we name these signatures?

# // Copyright 2025 Google LLC
# // SPDX-License-Identifier: Apache-2.0
#
// What are the types of these methods?
Option::is_some // ?
slice::get // ?
slice::get_unchecked_mut // ?
Option::as_ref // ?
str::from_utf8_unchecked_mut // ?
Rc::get_mut // ?
Vec::dedup_by_key // ?

// What should we name methods with these types?
fn ____(String) -> Self;
fn ____(&self) -> Option<&InnerType>; // details for InnerType do not matter.
fn ____(self, String) -> Self;
fn ____(&mut self) -> Option<&mut InnerType>;

• Go through the methods in the example with the class and discuss what the types of the functions should be.

• Go through the unnamed methods and brainstorm what names those methods should have.

  Answers for missing types:

  • Option::is_some(&self) -> bool
  • slice::get(&self /* &[T] */, usize) -> Option<&T>
  • slice::get_unchecked_mut(&self /* &[T] */, usize) -> &T (unsafe and simplified)
  • Option::as_ref(&self /* &Option<T> */) -> Option<&T>
  • str::from_utf8_unchecked_mut(v: &mut [u8]) -> &mut str (unsafe)
  • Rc::get_mut(&mut self /* &mut Rc<T> */) -> Option<&mut T> (simplified)
  • Vec::dedup_by_key<K: PartialEq>(&mut self /* &mut Vec<T> */, key: impl FnMut(&mut T) -> K) (simplified)

  Answers for missing names:

  • fn from_string(String) -> Self
  • fn inner(&self) -> Option<&InnerType> or as_ref, depending on context
  • fn with_string(self, String) -> Self
  • fn inner_mut(&mut self) -> Option<&mut InnerType> or as_ref_mut, depending on context