PatternUtils

This crate provides handy procedural macros for implementing common design patterns in Rust.

Features

• Builder derive macro
  Implements the Builder pattern by generating an associated Builder struct with fluent setter methods and flexible configuration options.

• observer macro (for traits)
  Implements the Observer pattern by generating a Publisher struct for the specified trait, allowing multiple observers to subscribe to instances of types implementing that trait.

Example

use patternutils::Builder;

#[derive(Builder)]
#[builder_attr(name = "CommandCreator", opt_in)]
struct Command {
    #[builder_field(name = "value", include = true)]
    definition: String,

    #[builder_field(include = true)]
    arg_count: usize,

    accepted_flag_fallback: fn(val: usize) -> usize,
    childs: Vec<Command>,
}

let mut builder = Command::builder();
let command = builder
    .value(String::from("my-command"))
    .arg_count(3)
    .build(|val| val + 5, vec![]);

assert_eq!(command.definition, String::from("my-command"));
assert_eq!(command.arg_count, 3);
assert_eq!((command.accepted_flag_fallback)(67), 72);
assert_eq!(command.childs.len(), 0);