Impl New

A procedural macro to generate a new function for your struct.

Add to your project

Add this to your Cargo.toml:

[dependencies]
impl_new = "0.1.0"

Or run this command in your workspace:

cargo add impl_new

Usage

Is simple, just derive the impl_new::New proc macro on your struct and it will generate a new function for you.

For Named Fields

#[derive(impl_new::New)]
struct Foo {
    name: String,
    age: usize,
}

// The generated code will look like this:
// impl Foo {
//     pub fn new(name: impl Into<String>, age: Into<usize>) -> Self {
//         Self { name: name.into(), age: age.into() }
//     }
// }

fn main() {
    let foo = Foo::new("Hello", 42usize); // Will use `Into::into` to convert the arguments to the fields types.
    assert_eq!(foo.name, "Hello".to_string());
    assert_eq!(foo.age, 42);
}

With Attributes

#[derive(impl_new::New)]
struct Foo {
    #[impl_new(name = "user_name")]
    name: String,
    #[impl_new(name = "user_age")]
    age: usize,
}

// The generated code will look like this:
// impl Foo {
//     pub fn new(user_name: impl Into<String>, user_age: Into<usize>) -> Self {
//         Self { name: user_name.into(), age: user_age.into() }
//     }
// }

fn main() {
    let foo = Foo::new("Hello", 42usize); // Will use `Into::into` to convert the arguments to the fields types.
    assert_eq!(foo.name, "Hello".to_string());
    assert_eq!(foo.age, 42);
}

For Unnamed Fields

Note: The #[impl_new(name = "name")] attribute is required for unnamed fields.

#[derive(impl_new::New)]
struct Foo(#[impl_new(name = "name")] String, #[impl_new(name = "age")] usize);

// The generated code will look like this:
// impl Foo {
//     pub fn new(name: impl Into<String>, age: Into<usize>) -> Self {
//         Self(name.into(), age.into())
//     }
// }

fn main() {
    let foo = Foo::new("Hello", 42usize); // Will use `Into::into` to convert the arguments to the fields types.
    assert_eq!(foo.0, "Hello".to_string());
    assert_eq!(foo.1, 42);
}

Attributes

• #[impl_new(name = "name")]: Use this attribute to change the name of the argument in the generated new function.

License

This project is licensed under the MIT license.