Nutype 0.5.0: the newtype with guarantees supports custom errors

Release notes: https://github.com/greyblake/nutype/releases/tag/v0.5.0

README: https://github.com/greyblake/nutype

What is nutype?

Nutype is a proc macro that adds sanitization and validation to newtypes, ensuring values always pass checks, even with serde deserialization.

What is new in nutype 0.5.0?

Nutype 0.5.0 allows users to define custom error types and validation logic, offering more flexibility while maintaining sanitization and validation guarantees.

Example

use nutype::nutype;

// Define a newtype `Name` with custom validation logic and a custom error type `NameError`.
// If validation fails, `Name` cannot be instantiated.
#[nutype(
    validate(with = validate_name, error = NameError),
    derive(Debug, AsRef, PartialEq),
)]
struct Name(String);

// Custom error type for `Name` validation.
// You can use `thiserror` or similar crates to provide more detailed error messages.
#[derive(Debug, PartialEq)]
enum NameError {
    TooShort { min: usize, length: usize },
    TooLong { max: usize, length: usize },
}

// Validation function for `Name` that checks its length.
fn validate_name(name: &str) -> Result<(), NameError> {
    const MIN: usize = 3;
    const MAX: usize = 10;
    let length = name.encode_utf16().count();

    if length < MIN {
        Err(NameError::TooShort { min: MIN, length })
    } else if length > MAX {
        Err(NameError::TooLong { max: MAX, length })
    } else {
        Ok(())
    }
}

fn main() {
    // Example usage: attempt to create a `Name` instance with an invalid value.
    assert_eq!(Name::try_new("Fo"), Err(NameError::TooShort { min: 3, length: 2 }));
}

The sponsors ❤️

A big shoutout to the true sponsors of this release - my in-laws! Thanks for taking care of my wife and kid, giving me a free weekend to work on Nutype!