from.md

minutes	2

from

A constructor function, strongly implying "type conversion".

# // Copyright 2025 Google LLC
# // SPDX-License-Identifier: Apache-2.0
#
impl Duration {
    fn from_days(days: u64) -> Duration;
}

impl i32 {
    fn from_ascii(src: &[u8]) -> Result<i32, ParseIntError>;
}

impl u32 {
    fn from_le_bytes(bytes: [u8; 4]) -> u32;
}

Details

• Prefix for constructor-style, From-trait-style functions.

• These functions can take multiple arguments, but usually imply the user is doing more of the work than a usual constructor would.

• new is still preferred for most constructor-style functions, the implication for from is transformation of one data type to another.