support setting output verbosity

This changes the internal use of echo to use a logger instead of sys.stdout.write.

This uses the stdlib logging library, with the common convention of logger = logging.getLogger(__name__), so that all watchdog logs are under the "watchdog" logging context.

Finally, this adds -q/--quiet and -v/--verbose command line options to watchmedo.

src/watchdog/tricks/__init__.py

@@ -41,6 +41,8 @@
 
 """
 
+import functools
+import logging
 import os
 import signal
 import subprocess
@@ -50,6 +52,10 @@
 from watchdog.events import PatternMatchingEventHandler
 
 
+logger = logging.getLogger(__name__)
+echo_events = functools.partial(echo.echo, write=lambda msg: logger.info(msg))
+
+
 class Trick(PatternMatchingEventHandler):
 
     """Your tricks should subclass this class."""
@@ -80,19 +86,19 @@ class LoggerTrick(Trick):
     def on_any_event(self, event):
         pass
 
-    @echo.echo
+    @echo_events
     def on_modified(self, event):
         pass
 
-    @echo.echo
+    @echo_events
     def on_deleted(self, event):
         pass
 
-    @echo.echo
+    @echo_events
     def on_created(self, event):
         pass
 
-    @echo.echo
+    @echo_events
     def on_moved(self, event):
         pass
 
@@ -202,7 +208,7 @@ def kill_process(stop_signal):
                     pass
         self.process = None
 
-    @echo.echo
+    @echo_events
     def on_any_event(self, event):
         self.stop()
         self.start()

src/watchdog/watchmedo.py

@@ -60,7 +60,8 @@ def _split_lines(self, text, width):
         return text.splitlines()
 
 
-epilog = '''Copyright 2011 Yesudeep Mangalapilly <yesudeep@gmail.com>.
+epilog = '''\
+Copyright 2011 Yesudeep Mangalapilly <yesudeep@gmail.com>.
 Copyright 2012 Google, Inc & contributors.
 
 Licensed under the terms of the Apache license, version 2.0. Please see
@@ -69,6 +70,7 @@ def _split_lines(self, text, width):
 cli = ArgumentParser(epilog=epilog, formatter_class=HelpFormatter)
 cli.add_argument('--version', action='version', version=VERSION_STRING)
 subparsers = cli.add_subparsers(dest='top_command')
+command_parsers = {}
 
 
 def argument(*name_or_flags, **kwargs):
@@ -94,6 +96,11 @@ def decorator(func):
                                    description=desc,
                                    aliases=cmd_aliases,
                                    formatter_class=HelpFormatter)
+        verbosity_group = parser.add_mutually_exclusive_group()
+        verbosity_group.add_argument('-q', '--quiet', dest='verbosity',
+                                     action='append_const', const=-1)
+        verbosity_group.add_argument('-v', '--verbose', dest='verbosity',
+                                     action='append_const', const=1)
         for arg in args:
             parser.add_argument(*arg[0], **arg[1])
             parser.set_defaults(func=func)
@@ -397,7 +404,8 @@ def log(args):
     from watchdog.tricks import LoggerTrick
 
     if args.trace:
-        echo.echo_class(LoggerTrick)
+        class_module_logger = logging.getLogger(LoggerTrick.__module__)
+        echo.echo_class(LoggerTrick, write=lambda msg: class_module_logger.info(msg))
 
     patterns, ignore_patterns =\
         parse_patterns(args.patterns, args.ignore_patterns)
@@ -637,9 +645,23 @@ def main():
     args = cli.parse_args()
     if args.command is None:
         cli.print_help()
-    else:
-        args.func(args)
+        return 1
+
+    verbosity = sum(args.verbosity)
+    if verbosity < -1:
+        print("Error: -q/--quiet may be specified only once.", file=sys.stderr)
+        command_parsers[args.top_command].print_help()
+        return 1
+    if verbosity > 2:
+        print("Error: -v/--verbose may be specified up to 2 times.", file=sys.stderr)
+        command_parsers[args.top_command].print_help()
+        return 1
+    log_level = ['ERROR', 'WARNING', 'INFO', 'DEBUG'][1 + verbosity]
+    logging.getLogger('watchdog').setLevel(log_level)
+
+    args.func(args)
+    return 0
 
 
 if __name__ == '__main__':
-    main()
+    sys.exit(main())