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# Copyright 2015 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Implementation of the flags interface."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import argparse
_global_parser = argparse.ArgumentParser()
class _FlagValues(object):
def __init__(self):
"""Global container and accessor for flags and their values."""
self.__dict__['__flags'] = {}
self.__dict__['__parsed'] = False
def _parse_flags(self):
result, _ = _global_parser.parse_known_args()
for flag_name, val in vars(result).items():
self.__dict__['__flags'][flag_name] = val
self.__dict__['__parsed'] = True
def __getattr__(self, name):
"""Retrieves the 'value' attribute of the flag --name."""
if not self.__dict__['__parsed']:
self._parse_flags()
if name not in self.__dict__['__flags']:
raise AttributeError(name)
return self.__dict__['__flags'][name]
def __setattr__(self, name, value):
"""Sets the 'value' attribute of the flag --name."""
if not self.__dict__['__parsed']:
self._parse_flags()
self.__dict__['__flags'][name] = value
def _define_helper(flag_name, default_value, docstring, flagtype):
"""Registers 'flag_name' with 'default_value' and 'docstring'."""
_global_parser.add_argument("--" + flag_name,
default=default_value,
help=docstring,
type=flagtype)
# Provides the global object that can be used to access flags.
FLAGS = _FlagValues()
def DEFINE_string(flag_name, default_value, docstring):
"""Defines a flag of type 'string'.
Args:
flag_name: The name of the flag as a string.
default_value: The default value the flag should take as a string.
docstring: A helpful message explaining the use of the flag.
"""
_define_helper(flag_name, default_value, docstring, str)
def DEFINE_integer(flag_name, default_value, docstring):
"""Defines a flag of type 'int'.
Args:
flag_name: The name of the flag as a string.
default_value: The default value the flag should take as an int.
docstring: A helpful message explaining the use of the flag.
"""
_define_helper(flag_name, default_value, docstring, int)
def DEFINE_boolean(flag_name, default_value, docstring):
"""Defines a flag of type 'boolean'.
Args:
flag_name: The name of the flag as a string.
default_value: The default value the flag should take as a boolean.
docstring: A helpful message explaining the use of the flag.
"""
# Register a custom function for 'bool' so --flag=True works.
def str2bool(v):
return v.lower() in ('true', 't', '1')
_global_parser.add_argument('--' + flag_name,
nargs='?',
const=True,
help=docstring,
default=default_value,
type=str2bool)
_global_parser.add_argument('--no' + flag_name,
action='store_false',
dest=flag_name)
# The internal google library defines the following alias, so we match
# the API for consistency.
DEFINE_bool = DEFINE_boolean # pylint: disable=invalid-name
def DEFINE_float(flag_name, default_value, docstring):
"""Defines a flag of type 'float'.
Args:
flag_name: The name of the flag as a string.
default_value: The default value the flag should take as a float.
docstring: A helpful message explaining the use of the flag.
"""
_define_helper(flag_name, default_value, docstring, float)
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