File watcher

[Boscillator]

Added file and directory watching flag. This is as requested in issue #99.
Usage:

coconut --watch examples/example.coco
coconut --watch examples

I did not use the watchdogs library because I wanted to keep dependencies minimal.

[evhub]

Looks good--just a couple of things that either you can fix now or I will fix when I merge it:

• Should never have a while True loop without some sort of time.sleep call to prevent it from taking up too much CPU time.
• Your watch function can't just call plain compile_path(source), it needs to respect all of the other arguments that might have been passed, thus I would make the call to watch replace the call to compile_path in if args.source is not None: such that watch takes all the same arguments, and then passes them along to compile_path when it calls it.

[Boscillator]

Ok, I'll work on it.

[candeira]

Watching files by looping and looking at times is far from good practice, especially when there exist libraries that hook into the host OS and provide you with callbacks when files change:

I use gamin:

• https://people.gnome.org/~veillard/gamin/python.html
  But there are other more recent entrants like watchdog:
• https://github.com/gorakhargosh/watchdog

[Boscillator]

I was trying to keep dependencies to a minimum, but I'll look into it.

[evhub]

I think introducing more required dependencies is not a good idea, but if you just put the import statement inside of the watch function, then Coconut remains usable by anyone who doesn't have the dependency and best practices can still be maintained.

[Boscillator]

Ok, so the problem with that is watchdogs wants me to subclass one of their classes. This would mean I would need to declare the class in the watch function, which would be ugly.
The other option would be to create a watch.py file, containing the watch function and the class and watchdogs imported at the top, and only import that the watch function needs to be called.
Does that seam like a good plan.

[Boscillator]

Ok, it now uses watchdogs.

[evhub]

Looks good! I'll try to merge it soon.