dependence

dependence brings dependency injection to node.js.

Manage your functions, variables and classes easily by turning them into dependencies. Get your modules under control.

Install

$ npm install dependence --save

Benefits

• Faster code producing by simply require dependencies in the constuctor parameter list.
• Better unit testing by easily mockup dependencies.

Example using dependence:

// Resolves the standard modules 'fs' and 'path' automatically
module.exports = function(fs, path) {
	return function(dirName, fileName) {
      return fs.readFileSync(path.join(dirName, fileName));
   }
};

Default way:

// No way to mock up those modules ...
var fs = require('fs');
var path = require('path');

module.exports = function(dirName, fileName) {
   return fs.readFileSync(path.join(dirName, fileName));
};

Usage

Shared dependency

var dependencies = require('dependence')();
var assert = require('assert');

dependencies.register('level', 1);

dependencies.register('nextLevel', function(level) {
   return level + 1 // level equals 1
});

dependencies.resolve(function(nextLevel) {
   assert.equal(nextLevel, 2);
});

Unshared dependency

var dependencies = require('dependence')();
var assert = require('assert');

var i = 0;
function counterDependecy() {
   return ++i;
}
counterDependecy.shared = false; // Default: true

dependencies.register('counter', counterDependecy);

dependencies.resolve(function(counter) {
   assert.equal(counter, 1);
});

dependencies.resolve(function(counter) {
   assert.equal(counter, 2); // would be 1 if 'shared' was true or undefined
});

Require explicitly

var dependencies = require('dependence')();
var assert = require('assert');

dependencies.register("Who is there?", "John");

function talkToJohn(whoIsThere) {
	assert.equal(whoIsThere, "John");
	done();
};

talkToJohn.require = ['Who is there?'];

dependencies.resolve(talkToJohn);

Options

• shared (default: true) - Defines the default value for sharing dependencies. Each dependency can overwrite this value by setting its own 'shared' attriute.
• node (default: true) - Set whether dependence should automatically try to require node modules if no dependency was found or not.
• src (default: undefined) - Creates a dependency provider that returns dependencies of .js files on the fly.

var dependencies = require('dependence')({
	shared: false, // default: true
   node: true, // default: true
   src: __dirname + "/lib/**/*.js" // default: null
});

This equals shared: false ...

var dependencies = require('dependence')(false);

Following equals src: __dirname + "/lib/**/*.js" ...

var dependencies = require('dependence')(__dirname + "/lib/*.js");

If using src: lib/nextLevel.js

module.exports = function(level) {
	return level + 1;
};

You can also write this angular style:

module.exports = ['level', function(level) {
	return level + 1;
}];

License

MIT © Alexander Löhn