touch the target file when any file in source directory changed, useful for auto reload apache wsgi.

auto_reload.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import time

import optparse

from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler


def touch(fname, times=None):
    """
    borrow from http://stackoverflow.com/questions/1158076/implement-touch-using-python
    emulate the touch command on linux
    """
    with file(fname, 'a'):
        os.utime(fname, times)


class FileChangeHandler(FileSystemEventHandler):

    def __init__(self, target):
        self.target = target

    def on_modified(self, event):
        if not event.is_directory and event.src_path.endswith(".py"):
            touch(self.target)

if __name__ == "__main__":
    p = optparse.OptionParser()
    p.add_option('--source', '-s', default='.')
    p.add_option('--target', '-t', default='.')

    options, arguments = p.parse_args()

    event_handler = FileChangeHandler(options.target)
    observer = Observer()
    observer.schedule(event_handler, path=options.source, recursive=True)
    observer.start()
    try:
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        observer.stop()
    observer.join()