fondant 0.1.2

Macro based library to take the boilerplate out of configuration handling


Documentation · Architecture · Usage · Customization · Todo

fondant is a macro based library to take the boilerplate out of configuration handling. All you need to do is derive the Configure trait on your struct, and fondant will decide where to store it and and how to do so safely.

Most of fondant is based off the confy crate, with a couple of extra features:

  • support for json, yaml and toml
  • support for custom config paths
  • support for custom config file names

Usage (Full Documentation)

Drop this in your Cargo.toml to get started:

fondant = "0.1.0"

Derive the macro:

// the struct has to derive Serialize, Deserialize and Default
use fondant::Configure;
use serde::{Serialize, Deserialize};

#[derive(Configure, Serialize, Deserialize, Default)]
#[config_file = "config.toml"]
struct AppConfig {
    port: u32,
    username: String,

fn main() {
    // use `load` to load the config file
    // loads in Default::default if it can't find one
    let mut conf = AppConfig::load().unwrap();

    // do stuff with conf
    conf.port = 7878;

    // call `store` to save changes;

Find more examples and options at


fondant is split into 3 separate crates:

  • fondant_deps: external crates and utils that fondant requires
  • fondant_derive: core macro definitions
  • fondant: the user facing library that brings it all together

This slightly strange architecture arose because of some limitations with proc-macro crates and strict cyclic dependencies in cargo. All you need is the fondant crate.


  • improve error types
  • use syn::Error and syn::Result to report macro errors
  • write docs
  • write test suite
  • bundle and publish to