baggy

This package has been deprecated. Please use ziploc for new projects. The purpose of this package is to provide a way to resolve types asynchronously. Let's take a look at the simplest example:

var Bag = require('baggy');
var bag = new Bag();

bag.create('One')
  .from(function (done) {
    done(null, 1);
  });

bag.resolve('One', function (error, one) {
  console.log(one); // 1
});

We can also create dependencies on other types:

var Bag = require('baggy');
var bag = new Bag();

bag.create('One')
  .from(function (done) {
    done(null, 1);
  });

bag.create('Two')
  .from('One', function (one, done) {
    done(null, one + one);
  });

bag.create('Three')
  .from('One', 'Two', function (one, two, done) {
    done(null, one + two);
  });

bag.resolve('Three', function (error, three) {
  console.log(three); // 3
});

The syntax is nice if you have a collection of static functions, but what if you already have an object with methods? No worries. No need to repeat yourself.

var Bag = require('baggy');
var bag = new Bag();

bag.use({
  getOne: function (done) {
    done(null, 1);
  },

  getTwoFromOne: function (one, done) {
    done(null, one + one);
  },

  getThreeFromOneAndTwo: function (one, two, done) {
    done(null, one + two);
  }
});

bag.resolve('Three', function (error, three) {
  console.log(three); // 3
});

In some cases you will want to resolve a derived type without persisting its dependencies. This is also supported.

var Bag = require('baggy');
var bag = new Bag();

bag.create('Power')
  .from('Base', 'Exponent', function (base, exponent, done) {
    done(null, Math.pow(base, exponent));
  });

bag.given('Base', 2)
  .given('Exponent', 3)
  .resolve('Power', function (error, power) {
    console.log(power); // 8
  });

bag.given('Base', 3)
  .given('Exponent', 2)
  .resolve('Power', function (error, power) {
    console.log(power); // 9
  });

bag.resolve('Base', function (error) {
  console.error(error); // [TypeError: Base]
});

bag.resolve('Exponent', function (error) {
  console.error(error); // [TypeError: Exponent]
});

Pull requests and bug reports are welcome, as always.