hot-reload.sh

#!/usr/bin/env python3
import os
import sys
import time
import subprocess

## usage
## ./hot-reload.sh [directories] <command>
## Example: ./hot-reload.sh dir1 dir2 dir3 'make'

sources = sys.argv[1:]
command = sources.pop()
proc = None

flatten = lambda lists: [item for sublist in lists for item in sublist]

retrive_files = lambda source: [os.path.join(root, file) for root, _, files in os.walk(source) for file in files]
filelists = lambda sources: [retrive_files(source) for source in sources]

transform_to_map = lambda _files: {file: os.path.getctime(file) for file in _files}

_files = flatten(filelists(sources))
_files_stamps = transform_to_map(_files)


def run_command(command):
    if proc:
        proc.kill()
        time.sleep(2)
    return subprocess.Popen(command, shell=True)

proc = run_command(command)

while True:
    time.sleep(2)
    # see if there are new files added
    changed = 0
    for file in _files_stamps:
        mtime = os.path.getctime(file)
        prv_mtime = _files_stamps[file]

        if prv_mtime != mtime:
            _files_stamps[file] = mtime        
            changed = 1
            break
        
    if changed == 1:
        print("file change detected")
        proc = run_command(command)