Node.js scope error

I'm getting the following error :

/Users/nblavoie/Desktop/HotPie/HotPie/apps/authentication/routes.coffee:6
  app.get('/login', function(req, res) {
  ^
ReferenceError: app is not defined
    at Object.<anonymous> (/Users/nblavoie/Desktop/HotPie/HotPie/apps/authentication/routes.coffee:6:3)
    at Object.<anonymous> (/Users/nblavoie/Desktop/HotPie/HotPie/apps/authentication/routes.coffee:15:4)
    at Module._compile (module.js:449:26)
    at Object.require.extensions..coffee (/Users/nblavoie/Desktop/HotPie/HotPie/node_modules/coffee-script/lib/coffee-script/coffee-script.js:22:21)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.require (module.js:362:17)
    at require (module.js:378:17)
    at Object.<anonymous> (/Users/nblavoie/Desktop/HotPie/HotPie/app.js:31:1)
    at Module._compile (module.js:449:26)

While trying to pass the (app) variable to the following require :

/**
 * Module dependencies.
 */

require('coffee-script');

var express = require('express')
  , http = require('http')
  , path = require('path');

var app = express();

app.configure(function(){
  app.set('port', process.env.PORT || 3000);
  app.set('views', __dirname + '/views');
  app.set('view engine', 'jade');
  app.use(express.favicon());
  app.use(express.logger('dev'));
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use(app.router);
  app.use(express.static(path.join(__dirname, 'public')));
});

app.configure('development', function(){
  app.use(express.errorHandler());
});

// Routes
**require('./apps/authentication/routes')(app);**

http.createServer(app).listen(app.get('port'), function(){
  console.log("Express server listening on port " + app.get('port'));
});

Using the app variable in the following file :

routes = (app) -> 
app.get '/login', (req, res) ->
    res.render 'views/login',
        title: 'Login'
        stylesheet: 'login'
module.exports = routes

I know that the variable scope is different from one JS file to another. But why does the following line :

require('./apps/authentication/routes')(app);

Doesn't pass the app variable?

Right here:

ReferenceError: app is not defined
    at Object.<anonymous> (/Users/nblavoie/Desktop/HotPie/HotPie/apps/authentication/routes.coffee:6:3)

The error isn't in app.js, it's in your CoffeeScript file. Check out what it's compiling to:

var routes;

routes = function(app) {};

app.get('/login', function(req, res) {
  return res.render('views/login', {
    title: 'Login',
    stylesheet: 'login'
  });
});

module.exports = routes;

Notice that routes is an empty function? Yep, you missed an indent. Changing your CoffeeScript to the following should fix it (notice the indentation of app.get and everything after it):

routes = (app) ->
    app.get '/login', (req, res) ->
        res.render 'views/login',
            title: 'Login',
            stylesheet: 'login'

module.exports = routes

CoffeeScript is very sensitive to indentation. This code should work:

routes = (app) -> 
    app.get '/login', (req, res) ->
        res.render 'views/login',
            title: 'Login'
            stylesheet: 'login'
module.exports = routes