Python.tornado.2.tornado.options

记录Tornado-4.0.2源码的阅读，学习，分析

options.py

1. imports 部分

1.1 __future__

 from __future__ import absolute_import, division, print_function, with_statement

future_statement 即：from __futuren import XXX. 参见 XiaoKL学Python（C）__future__

1.2 other imports from Python Library

 import datetime
 import numbers
 import re
 import sys
 import os
 import textwrap

1.3 other imports from tornado

 from tornado.escape import _unicode
 from tornado.log import define_logging_options
 from tornado import stack_context
 from tornado.util import basestring_type, exec_in

2. 定义的类

2.1 OptionParser类

该类负责解析命令行的Option, 每个option被抽象为类_Option的对象。

2.2 _Option类

代表命令行上的每个option，该类为内部类。

2.3 全局的OptionParser对象

定义了一个全局的OptionParser对象。options.py提供的接口都是在该对象上进行操作的。

末尾调用了以下接口来将log相关的option添加到options.py模块中。

 define_logging_options(options)

3. options.py对外提供的接口

[Todo]

3.1 define

 def define(name, default=None, type=None, help=None, metavar=None,
            multiple=False, group=None, callback=None)

3.2 parse_command_line

 def parse_config_file(path, final=True)

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Learn From options.py

1. sys模块

import sys

https://docs.python.org/2/library/sys.html?highlight=sys#module-sys

sys._getframe([depth])

"Return a frame object from the call stack. If optional integer depth is given, return the frame

object that many calls below the top of the stack. If that is deeper than the call stack, ValueError

is raised. The default fordepth is zero, returning the frame at the top of the call stack."

在options.py中的使用，在OptionParser类的define方法的实现中：

         frame = sys._getframe(0)

2. inspect 模块

https://docs.python.org/2/library/inspect.html

"The inspect module provides several useful functions to help get information about live

objects such as modules, classes, methods, functions, tracebacks, frame objects, and code objects. "

该模块中包含 frame 类型(即: sys._getframe() 返回值的类型 )的说明。

3. unittest.mock.patch

mock 模块

Python中的单元测试。

4. 不了解的语法

4.1 return xxxx if yyyy else zzzz

     def value(self):
         return self.default if self._value is _Option.UNSET else self._value

4.2 xxx for yyy, zzz in ttt

     _TIMEDELTA_ABBREV_DICT = dict(
         (abbrev, full) for full, abbrevs in _TIMEDELTA_ABBREVS
         for abbrev in abbrevs)

4.3 正则表达式

     _FLOAT_PATTERN = r'[-+]?(?:\d+(?:\.\d*)?|\.\d+)(?:[eE][-+]?\d+)?'

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Reference

1. http://www.tornadoweb.org/en/stable/options.html