Bridging the Efficiency Gap Between FromStr and String

"The FromStr trait in Rust allows for converting &str into other types, but using it with a String can lead to unnecessary cloning."

"Introducing a new FromString trait facilitates direct conversion from String, avoiding performance issues by handling cases that would otherwise create clones."

"Implementing FromString as a blanket implementation for types that implement FromStr provides a seamless conversion experience while managing errors effectively."

"Using transmute_copy in the FromString trait allows efficient handling of String-to-String conversions without the overhead of cloning, enhancing performance."

The article discusses the limitations of the FromStr trait in Rust, which converts &str to various types but can lead to inefficiencies when working with String inputs requiring conversions. To improve performance and avoid unnecessary cloning, the author proposes a new trait called FromString. This trait allows direct conversion from String to compatible types, including a no-op for String-to-String conversions. It also includes a blanket implementation for types that implement FromStr, effectively handling errors by leveraging Rust's Error conversion and utilizing transmute_copy for optimized performance in conversions.

Read at Armin Ronacher's Thoughts and Writings