tensorflow2：tf.app.run()

在很多TensorFlow公布的Demo中，都有这样的代码存在，如下，这是干什么的呢？

我们来看一下源代码：

# tensorflow/tensorflow/python/platform/default/_app.py  

# 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.
# ==============================================================================  

"""Generic entry point script."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function  

import sys  

from tensorflow.python.platform import flags  

def run(main=None):
  f = flags.FLAGS
  f._parse_flags()
  main = main or sys.modules['__main__'].main
  sys.exit(main(sys.argv))  

处理flag解析，然后执行main函数，那么flag解析是什么意思呢？诸如这样的：

tf.app.flags.DEFINE_boolean("self_test", False, "True if running a self test.")
tf.app.flags.DEFINE_boolean('use_fp16', False,
                            "Use half floats instead of full floats if True.")
FLAGS = tf.app.flags.FLAGS