Default Struct Builder

Generates builder methods of every field of a struct. It is meant to be used on structs that implement Default. There is no separate builder struct generated and no need to call a build() method at the end or .unwrap().

This crate is used by the crate leptos-use for the option structs that can be passed to the various functions.

Installation

In your project folder run

cargo add default-struct-builder

Usage

It is very easy to use:

use default_struct_builder::DefaultBuilder;

#[derive(DefaultBuilder, Default)]
pub struct SomeOptions {
    throttle: f64,

    #[builder(into)]
    offset: Option<f64>,

    #[builder(skip)]
    not_included: u32,
}

you can then use the struct like this:

let options = SomeOptions::default().offset(4.0);

assert_eq!(options.offset, Some(4.0));
assert_eq!(options.throttle, 0.0);
assert_eq!(options.not_included, 0);

How it works

The derive macro generates the following code:

impl SomeOptions {
    pub fn throttle(self, value: f64) -> Self {
        Self {
            throttle: value,
            ..self
        }
    }

    pub fn offset<T>(self, value: T) -> Self
    where
        T: Into<Option<f64>>,
    {
        Self {
            offset: value.into(),
            ..self
        }
    }
}

Related Work

For more general purposes please check out the much more powerful derive_builder crate.