A more intelligent less file compiler.

watchless.py

# -*- coding: utf-8 -*-

"""
Watchless will compile your less files whenever it detects changes.
Accepts one argument, the path where your less files are stored.

Say your less files are store in /static/less and it contains the file
layout.less, watchless will compile it and store the compiled css file
in /static/css/layout.css.

Usage:
    python watchless.py <path to less directory>
"""

import sys
import os
import pyinotify


wm = pyinotify.WatchManager()
mask = pyinotify.IN_MODIFY | pyinotify.IN_CREATE


class EventHandler(pyinotify.ProcessEvent):

    def __init__(self, *args, **kwargs):
        self.css_root = kwargs.pop('css_root')
        self.less_root = kwargs.pop('less_root')

        if not os.path.exists(self.css_root):
            os.makedirs(self.css_root)

        super(EventHandler, self).__init__(*args, **kwargs)

    def _compile_less(self, less_file):
        if not less_file.endswith('.less'):
            return

        print "Compiling %s" % less_file

        # mirror mirror on the wall, is the directory present in css path
        parent_less_path = os.path.dirname(less_file)
        relative_less_path = parent_less_path.replace(self.less_root, '')[1:]
        parent_css_path = os.path.join(self.css_root, relative_less_path)
        if not os.path.exists(parent_css_path):
            os.makedirs(parent_css_path)

        filename, __ = os.path.splitext(os.path.basename(less_file))
        css_file = "%s.css" % os.path.join(parent_css_path, filename)
        os.system("lessc %(from)s > %(to)s -x" % {"from": less_file,
                                                  "to": css_file})

    def process_IN_MODIFY(self, event):
        self._compile_less(event.pathname)

    def process_IN_CREATE(self, event):
        self._compile_less(event.pathname)


if __name__ == '__main__':
    if len(sys.argv) != 2:
        print "You need to specify the path where .less files are located."
        sys.exit(1)

    if not os.path.exists(sys.argv[1]):
        print "The path you specified doesn't exist."
        sys.exit(1)

    LESS_ROOT = sys.argv[1]
    CSS_ROOT = os.path.join(os.path.split(LESS_ROOT)[0], 'css')

    handler = EventHandler(less_root=LESS_ROOT, css_root=CSS_ROOT)
    notifier = pyinotify.Notifier(wm, handler)
    wdd = wm.add_watch(LESS_ROOT, mask, rec=True, auto_add=True)
    print "Imma watch your less baby!"
    notifier.loop()