Hoisting + CPS example

example.js

// This the code in the npm multi-stage branch that removes a package directory.

function removeDir (pkg, log, next) {
  var modpath = path.join(path.dirname(pkg.path), '.' + path.basename(pkg.path) + '.MODULES')

  // Preserve any modules installed in this package, if any
  fs.rename(path.join(pkg.path, 'node_modules'), modpath, unbuildPackage)

  function unbuildPackage (renameEr) {
    npm.commands.unbuild(pkg.path, true, renameEr ? andRemoveEmptyParents(pkg.path) : moveModulesBack)
  }

  function andRemoveEmptyParents (path) {
    return function (er) {
      if (er) return next(er)
      removeEmptyParents(pkg.path)
    }
  }

  function moveModulesBack () {
    fs.readdir(modpath, makeTarget)
  }

  function makeTarget (readdirEr, files) {
    if (readdirEr) return cleanup()
    if (!files.length) return cleanup()
    mkdirp(path.join(pkg.path, 'node_modules'), function (mkdirEr) { moveModules(mkdirEr, files) })
  }

  function moveModules (mkdirEr, files) {
    if (mkdirEr) return next(mkdirEr)
    asyncMap(files, function (file, done) {
      var from = path.join(modpath, file)
      var to = path.join(pkg.path, 'node_modules', file)
      // we ignore errors here, because they can legitimately happen, for instance,
      // bundled modules will be in both node_modules folders
      fs.rename(from, to, function () { done() })
    }, cleanup)
  }

  function cleanup () {
    rimraf(modpath, afterCleanup)
  }

  function afterCleanup (rimrafEr) {
    if (rimrafEr) log.warn('finalize', rimrafEr)
    removeEmptyParents(path.resolve(pkg.path, '..'))
  }

  function removeEmptyParents (pkgdir) {
    fs.rmdir(pkgdir, function (er) {
      // FIXME: Make sure windows does what we want here
      if (er && er.code !== 'ENOENT') return next()
      removeEmptyParents(path.resolve(pkgdir, '..'))
    })
  }
}

The FIXME alludes to the fact that Windows doesn't always have the same error codes for the same conditions as Unix-like-OSes. Unfortunately, ENOENT is often replaced by EPERM. =/ This code will likely end up w/ a stat inserted prior to a then conditional rmdir.