zanzou

Zanzou

Something like Ruby port of immer.js

Installation

Add this line to your application's Gemfile:

gem 'zanzou'

And then execute:

$ bundle

Or install it yourself as:

$ gem install zanzou

Usage

With Zanzou.with_updates, you can create a modified copy of orig_obj with imperative style.

require 'zanzou'
orig_obj = {a: 1, b: 2}
p Zanzou.with_updates(orig_obj){|o| o[:b] = 3}
# => {a: 1, b: 3}
p orig_obj
# => {a: 1, b: 2}

Or you can just call .with_updates by requir'ing zanzou/install.

require 'zanzou/install'
orig_obj = {a: 1, b: 2}
p orig_obj.with_updates{|o| o[:b] = 3}
p orig_obj

Supported classes

Zanzou should work well with these objects.

• Array, Hash, String, numbers, true, false, nil

Normally other objects, say a Range, should be OK too. However, container classes (i.e. objects which contains other objects in it) need special treatment to be used with Zanzou.

Steps to add support for a container class:

• Define class XxxShadow < Zanzou::ShadowNode

See spec/zanzou_spec.rb for an example.

Known issues

Some methods of Array/Hash may does not work well. See the pending specs (git grep pending).

FYI immer.js does not have such problems because ES6 Proxy is very powerful - it reports object set/get even for methods like Array sort.

const hooks = {
    get(target, prop, receiver) {
      console.log({hook: "get", prop})
      return target[prop];
    },
    set(target, prop, value) {
      console.log({hook: "set", prop, value})
      return target[prop] = value;
    }
};

const obj = [5613,2348,2987,2387,7823,1987];
const pxy = new Proxy(obj, hooks);
pxy.sort();

// Output:
//   ...
//   { hook: 'get', prop: '4' }
//   { hook: 'get', prop: '5' }
//   { hook: 'set', prop: '0', value: 1987 }  // It reports all the set/get operations
//   { hook: 'set', prop: '1', value: 2348 }  // sort() does and thus immer.js can
//   { hook: 'set', prop: '2', value: 2387 }  // track movements of child elements.
//   { hook: 'set', prop: '3', value: 2987 }
//   { hook: 'set', prop: '4', value: 5613 }
//   { hook: 'set', prop: '5', value: 7823 }

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/yhara/zanzou.

How to run test

bundle exec rspec

License

The gem is available as open source under the terms of the MIT License.