Toml Example

A lib help generate toml example

Introduction

This crate provides the TomlExample trait and an accompanying derive macro.

Deriving TomlExample on a struct will provide to_example function help generate toml example file base documentation

• support #[serde(default)], #[serde(default = "function_name")] attributes (serde feature, opt-in)
• support #[serde(rename)], #[serde(rename_all = "renaming rules")], the renaming rules can be lowercase, UPPERCASE, PascalCase, camelCase, snake_case, SCREAMING_SNAKE_CASE, kebab-case, SCREAMING-KEBAB-CASE
• provide #[toml_example(default)], #[toml_example(default = 0)], #[toml_example(default = "default_string")] attributes
• The order matter of attribute macro, if #[serde(default = ..] and #[toml_example(default = ..)] existing at the same time with different value

Quick Example

use toml_example::TomlExample;

/// Config is to arrange something or change the controls on a computer or other device
/// so that it can be used in a particular way
#[derive(TomlExample)]
struct Config {
    /// Config.a should be a number
    a: usize,
    /// Config.b should be a string
    b: String,
    /// Optional Config.c is a number
    c: Option<usize>,
    /// Config.d is a list of number
    d: Vec<usize>,
    /// Config.e should be a number
    #[serde(default = "default_int")]
    e: usize,
    /// Config.f should be a string
    #[serde(default = "default_str")]
    f: String,
    /// Config.g should be a number
    #[toml_example(default =7)]
    g: usize,
    /// Config.f should be a string
    #[toml_example(default = "seven")]
    h: String,
}
fn default_int() -> usize {
    7
}
fn default_str() -> String {
    "seven".into()
}

Config::to_toml_example("example.toml");  // write example to a file
let example = Config::toml_example();

Toml example base on the doc string of each field

# Config is to arrange something or change the controls on a computer or other device
# so that it can be used in a particular way

# Config.a should be a number
a = 0

# Config.b should be a string
b = ""

# Optional Config.c is a number
# c = 0

# Config.d is a list of number
# d = [ 0, ]

# Config.e should be a number
e = 7

# Config.f should be a string
f = "seven"

# Config.g should be a number
g = 7

# Config.h should be a string
h = "seven"

Nesting Struct

A nesting struct wrap with Option<T>, Vec<T>, HashMap<String, T>, BTreeMap<String, T> are handled. Please add #[toml_example(nesting)], or #[toml_example(nesting = prefix)] on the field. #[toml_example(nesting)]

  /// Service with specific port
  #[derive(TomlExample)]
  struct Service {
      /// port should be a number
      #[toml_example(default = 80)]
      port: usize,
  }
  #[derive(TomlExample)]
  #[allow(dead_code)]
  struct Node {
      /// Services are running in the node
      #[toml_example(nesting)]
      #[toml_example(default = http)]
      services: HashMap<String, Service>,
  }

Node::toml_example() will be following string.

# Services are running in the node
# Service with specific port
[services.http]
# port should be a number
port = 80

If you want an optional field become a required field in example, place the #[toml_example(require)] on the field. If you want to skip some field you can use #[toml_example(skip)], the #[serde(skip)], #[serde(skip_deserializing)] also works.

use toml_example::TomlExample;
#[derive(TomlExample)]
struct Config {
    /// Config.a is an optional number
    #[toml_example(require)]
    a: Option<usize>,
    /// Config.b is an optional string
    #[toml_example(require)]
    b: Option<String>,
    #[toml_example(require)]
    #[toml_example(default = "third")]
    c: Option<String>,
    #[toml_example(skip)]
    d: usize,
}

# Config.a is an optional number
a = 0

# Config.b is an optional string
b = ""

c = "third"