Add examples to opensource version.

	Change on 2016/09/30 by vrusinov <[email protected]>

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=134779382

examples/basic_usage.py

@@ -0,0 +1,26 @@
+#!/usr/bin/env python
+"""Example for basic usage of the flags library."""
+
+from google.apputils import app
+import gflags
+
+FLAGS = gflags.FLAGS
+
+# Flag names are globally defined!  So in general, we need to be
+# careful to pick names that are unlikely to be used by other libraries.
+# If there is a conflict, we'll get an error at import time.
+gflags.DEFINE_string('name', 'Mr. President', 'your name')
+gflags.DEFINE_integer('age', None, 'your age in years', lower_bound=0)
+gflags.DEFINE_boolean('debug', False, 'produces debugging output')
+gflags.DEFINE_enum('job', 'running', ['running', 'stopped'], 'job status')
+
+
+def main(argv):
+  if FLAGS.debug:
+    print 'non-flag arguments:', argv
+  print 'Happy Birthday', FLAGS.name
+  if FLAGS.age is not None:
+    print 'You are %d years old, and your job is %s' % (FLAGS.age, FLAGS.job)
+
+if __name__ == '__main__':
+  app.run()

examples/command_flags.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+"""Example for appcomands flag usage."""
+
+from __future__ import print_function
+
+from google.apputils import appcommands
+import gflags
+
+FLAGS = gflags.FLAGS
+
+
+class HelloWorld(appcommands.Cmd):
+
+  def __init__(self, name, flag_values, **kargs):
+    super(HelloWorld, self).__init__(name, flag_values, kargs)
+
+    # Define the new flag inside the __init__ function of the class.
+    gflags.DEFINE_bool('world', False, 'Display world as well',
+                      flag_values=flag_values)
+
+  def Run(self, argv):
+    # Output different things depending on flag value.
+    if FLAGS.world:
+      print('Hello world')
+    else:
+      print('Hello')
+
+
+def main(unused_argv):
+  appcommands.AddCmd('hello', HelloWorld, help_full='Runs hello world')
+
+
+if __name__ == '__main__':
+  appcommands.Run()

examples/libbar.py

@@ -0,0 +1,11 @@
+#!/usr/bin/env python
+"""Defines some other flags."""
+
+import gflags
+
+gflags.DEFINE_string('bar_gfs_path', '/gfs/path',
+                    'Path to the GFS files for libbar.')
+gflags.DEFINE_string('email_for_bar_errors', '[email protected]',
+                    'Email address for bug reports about module libbar.')
+gflags.DEFINE_boolean('bar_risky_hack', False,
+                     'Turn on an experimental and buggy optimization.')

examples/libfoo.py

@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+"""Defines some flags."""
+
+import gflags
+
+gflags.DEFINE_integer('num_replicas', 3, 'Number of replicas to start')
+gflags.DEFINE_boolean('rpc2', True, 'Turn on the usage of RPC2.')

examples/myscript.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+"""Adopts all flags from libfoo and one flag from libbar."""
+
+import gflags
+from gflags.examples import libbar  # pylint: disable=unused-import
+from gflags.examples import libfoo
+
+gflags.DEFINE_integer('num_iterations', 0, 'Number of iterations.')
+
+# Declare that all flags that are key for libfoo are
+# key for this module too.
+gflags.ADOPT_module_key_flags(libfoo)
+
+# Declare that the flag --bar_gfs_path (defined in libbar) is key
+# for this module.
+gflags.DECLARE_key_flag('bar_gfs_path')

examples/use_before_parse_broken.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+"""Broken due to access to flags before parsing."""
+
+from google.apputils import app
+import gflags
+
+# Defines string with default value of 'default value'
+gflags.DEFINE_string('test_flag', 'default value', 'Test flag')
+
+FLAGS = gflags.FLAGS
+
+# Assigns value of FLAGS.test_flag (string) to MY_CONST during module execution.
+# Since flags were not parsed yet FLAGS.test_flag will always return default
+# value of the flag.
+MY_CONST = FLAGS.test_flag
+
+
+def main(_):
+  print MY_CONST  # Will ALWAYS output 'default value'
+
+if __name__ == '__main__':
+  app.run()  # Does a lot of useful stuff, including parsing flags.

examples/use_before_parse_reset_broken.py

@@ -0,0 +1,17 @@
+#!/usr/bin/env python
+"""FLAGS.Reset() is evli."""
+
+import unittest
+import gflags
+
+FLAGS = gflags.FLAGS
+
+
+class CertCheckTest(googletest.TestCase):
+
+  def setUp(self):
+    FLAGS.Reset()  # Resets all flags, including stuff like test_srcdir.
+
+  def testFoo(self):
+    FLAGS.foo = 'bar'
+    self.assertEqual(2, 2)

examples/use_before_parse_variable_broken.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+"""Example of the code that accesses flags at top of the module."""
+
+import os
+import unittest
+import gflags
+
+FLAGS = gflags.FLAGS
+
+OUTPUT_DIR = os.path.join(FLAGS.my_dir, 'my_subdir')
+
+
+class MyTest(googletest.TestCase):
+
+  def setUp(self):
+    self.filename = os.path.join(OUTPUT_DIR, 'filename')

examples/use_before_parse_variable_fixed.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python
+"""Proposed fix."""
+
+import os
+import unittest
+import gflags
+
+FLAGS = gflags.FLAGS
+
+
+def _get_output_dir():
+  return os.path.join(FLAGS.my_dir, 'my_subdir')
+
+
+class MyTest(googletest.TestCase):
+
+  def setUp(self):
+    self.filename = os.path.join(_get_output_dir(), 'filename')

examples/validator.py

@@ -0,0 +1,14 @@
+#!/usr/bin/env python
+"""RegisterValidator example."""
+
+import gflags
+
+FLAGS = gflags.FLAGS
+
+gflags.DEFINE_integer('my_version', 0, 'Version number.')
+gflags.DEFINE_string('filename', None, 'Input file name', short_name='f')
+
+gflags.RegisterValidator('my_version',
+                        lambda value: value % 2 == 0,
+                        message='--my_version must be divisible by 2')
+gflags.MarkFlagAsRequired('filename')