watcher.nim

gistfile1.txt

## create a nimble dev task
## 
## task dev, "run watcher":
##   exec "nim c -r watcher.nim <src> <binary>"

import osproc, os, tables, times

let
  dir = if paramCount() > 0: paramStr(1) else: "src"
  bin = if paramCount() > 1: paramStr(2) else: "client"

proc start(): Process =
  discard execCmd "nimble build"
  startProcess("./" & bin, "", [], nil, {poEvalCommand, poStdErrToStdOut,
      poParentStreams})

proc getLastWrite(): Table[string, Time] =
  for f in walkDirRec(dir):
    result[f] = getFileInfo(f).lastWriteTime

var
  process = start()
  lastWrite = getLastWrite()

proc restart() =
  if not process.isNil:
    process.kill()
    process.close()
  process = start()

while true:
  let t = getLastWrite()
  if t != lastWrite:
    echo "Restarting"
    lastWrite = t
    restart()

  sleep(100)

could probably parse nimble config to get a better default binary name