use logging for controlling console output verbosity

.gitignore

@@ -25,3 +25,6 @@ pip-log.txt
 
 #Mr Developer
 .mr.developer.cfg
+
+#sample output
+*.log

cliff/app.py

@@ -2,6 +2,7 @@
 """
 
 import logging
+import logging.handlers
 import optparse
 import os
 import sys
@@ -13,7 +14,11 @@ class App(object):
     """Application base class.
     """
 
-    NAME = os.path.basename(sys.argv[0])
+    NAME = os.path.splitext(os.path.basename(sys.argv[0]))[0]
+
+    CONSOLE_MESSAGE_FORMAT = '%(message)s'
+    LOG_FILE_MESSAGE_FORMAT = '%(asctime)s %(levelname)s %(name)s %(message)s'
+    DEFAULT_VERBOSE_LEVEL = 1
 
     def __init__(self, description, version, command_manager):
         self.command_manager = command_manager
@@ -29,9 +34,17 @@ class App(object):
         self.parser.add_option(
             '-v', '--verbose',
             action='count',
-            dest='verbose',
+            dest='verbose_level',
+            default=self.DEFAULT_VERBOSE_LEVEL,
             help='Increase verbosity of output. Can be repeated.',
             )
+        self.parser.add_option(
+            '-q', '--quiet',
+            action='store_const',
+            dest='verbose_level',
+            const=0,
+            help='suppress output except warnings and errors',
+            )
         self.parser.add_option(
             '-h', action='help',
             help="show this help message and exit",
@@ -51,15 +64,43 @@ class App(object):
             factory = ep.load()
             cmd = factory(self, None)
             print('  %-13s  %s' % (name, cmd.get_description()))
-        raise SystemExit()
+        sys.exit(0)
+
+    def configure_logging(self):
+        """Create logging handlers for any log output.
+        """
+        root_logger = logging.getLogger('')
+
+        # Set up logging to a file
+        root_logger.setLevel(logging.DEBUG)
+        file_handler = logging.handlers.RotatingFileHandler(
+            self.NAME + '.log',
+            maxBytes=10240,
+            backupCount=1,
+            )
+        formatter = logging.Formatter(self.LOG_FILE_MESSAGE_FORMAT)
+        file_handler.setFormatter(formatter)
+        root_logger.addHandler(file_handler)
+
+        # Send higher-level messages to the console, too
+        console = logging.StreamHandler()
+        console_level = {0: logging.WARNING,
+                         1: logging.INFO,
+                         2: logging.DEBUG,
+                         }.get(self.options.verbose_level, logging.DEBUG)
+        console.setLevel(console_level)
+        formatter = logging.Formatter(self.CONSOLE_MESSAGE_FORMAT)
+        console.setFormatter(formatter)
+        root_logger.addHandler(console)
+        return
 
     def run(self, argv):
         if not argv:
             argv = ['-h']
-        app_options, remainder = self.parser.parse_args(argv)
-        # FIXME(dhellmann): set up logging based on verbosity flag
+        self.options, remainder = self.parser.parse_args(argv)
+        self.configure_logging()
         cmd_factory, cmd_name, sub_argv = self.command_manager.find_command(remainder)
-        cmd = cmd_factory(self, app_options)
+        cmd = cmd_factory(self, self.options)
         cmd_parser = cmd.get_parser(' '.join([self.NAME, cmd_name]))
         parsed_args = cmd_parser.parse_args(sub_argv)
         return cmd.run(parsed_args)

demoapp/cliffdemo/simple.py

@@ -1,3 +1,4 @@
+import logging
 
 from cliff.command import Command
 
@@ -5,5 +6,8 @@ from cliff.command import Command
 class Simple(Command):
     "A simple command that prints a message."
 
+    log = logging.getLogger(__name__)
+
     def run(self, parsed_args):
-        print 'hi!'
+        self.log.debug('debugging')
+        self.log.info('hi!')