python - tornado中使用parse_command_line(final=False) 没能理解final是做什么的

问题描述

大概知道parse_command_line是用来解析命令行的，但是不理解里面的final参数是作什么的。顺便咨询一下学习tonardo的学习资源（知道官方文档是最好的）和书籍

问题解答

通过这样，找到源代码，请自己看方法文档

If final is False, parse callbacks will not be run.

This is useful for applications that wish to combine configurationsfrom multiple sources.

def parse_command_line(self, args=None, final=True):'''Parses all options given on the command line (defaults to`sys.argv`).Note that ``args[0]`` is ignored since it is the program namein `sys.argv`.We return a list of all arguments that are not parsed as options.If ``final`` is ``False``, parse callbacks will not be run.This is useful for applications that wish to combine configurationsfrom multiple sources.'''if args is None: args = sys.argvremaining = []for i in range(1, len(args)): # All things after the last option are command line arguments if not args[i].startswith('-'):remaining = args[i:]break if args[i] == '--':remaining = args[i + 1:]break arg = args[i].lstrip('-') name, equals, value = arg.partition('=') name = self._normalize_name(name) if name not in self._options:self.print_help()raise Error(’Unrecognized command line option: %r’ % name) option = self._options[name] if not equals:if option.type == bool: value = 'true'else: raise Error(’Option %r requires a value’ % name) option.parse(value)if final: self.run_parse_callbacks()return remaining