Application level build script

app-build.js

/** build.js **/

var piler = require('piler')
  , bundles = require('bundles.json')
  , bundleTasks = []


// Try to load a build script for all of
// the bundles specified in bundles.json
bundles.forEach(function (bundle) {
  
  try {
    var build = require(bundle + '/build')
    bundleTasks.push(build)
  } catch (e) {
    // No build script for bundle
  }

})

piler
  .set('watch', true)
  .set('env', 'development')

piler.task({
  // ... some application level task
})

// Loop over the build scripts
// and load in their tasks
bundleTasks.forEach(function (tasks) {
  tasks(piler)
})

piler.run()

bundle-build.js

/** bundles/admin/build.js **/

module.exports = tasks

var processStylus = require('piler-process-stylus')
  , processJS = require('piler-process-js')


function tasks(piler) {

  piler.task('css',
    { items:
      [ { src: 'public/css/screen.styl'
        , dest: 'public/css/screen.css'
        }
      ]
    , process: processStylus
    })

  piler.task('js',
    { items:
      [ { dest: 'public/js/app.js'
        , srcs: [ 'public/js/a.js', 'public/js/b.js' ]
        }
      ]
    , process: processJS
    })

  piler.watch('public/css/*.styl', 'css')
  piler.watch('public/js/*.js', 'js')

}

Usage

$ node build

// And maybe use an options parser, eg: https://github.com/substack/node-optimist
// to configure piler through `piler.set('key', val)` options through cli:

$ node build --watch

$ node build --env development

I think a nice extension to this would be the ability to name and namespace tasks, so that you can specify which to run from the cli, eg:

// Only process the tasked named 'js' in the 'admin' namespace
node build admin:js

// Process a task named 'js' in any namespace
node build :js

// Process all of the tasks in the 'admin' namespace
node build admin:

Namespace API:

piler.namespace('admin', function (ns) {

  ns.task(
    { name: 'js'
    , items:
      [ { dest: 'public/js/app.js'
        , srcs: [ 'public/js/a.js', 'public/js/b.js' ]
        }
      ]
    , process: processJS
    , watch: 'public/js/*.js'
    })

})

I like the ideal of namespacing tasks. That could really help simplify the concept of sub-project builds.

I also like the way you bring the bundles in from the json. It is likely that the build order in the application will also be a build order for an application. I can't imagine how it might work, but at some point bundles may want to contribute to a global js file that the whole application uses.