tornado.options — Command-line parsing

A command line parsing module that lets modules define their own options.

Each module defines its own options which are added to the global option namespace, e.g.:

from tornado.options import define, options

define("mysql_host", default="127.0.0.1:3306", help="Main user DB")
define("memcache_hosts", default="127.0.0.1:11011", multiple=True,
       help="Main user memcache servers")

def connect():
    db = database.Connection(options.mysql_host)
    ...

The main() method of your application does not need to be aware of all of the options used throughout your program; they are all automatically loaded when the modules are loaded. However, all modules that define options must have been imported before the command line is parsed.

Your main() method can parse the command line or parse a config file with either:

tornado.options.parse_command_line()
# or
tornado.options.parse_config_file("/etc/server.conf")

Command line formats are what you would expect (--myoption=myvalue). Config files are just Python files. Global names become options, e.g.:

myoption = "myvalue"
myotheroption = "myothervalue"

We support , , ints, and floats (just pass a type kwarg to ). We also accept multi-value options. See the documentation for below.

is a singleton instance of , and the top-level functions in this module (, , etc) simply call methods on it. You may create additional instances to define isolated sets of options, such as for subcommands.

注解

By default, several options are defined that will configure the standard module when or are called. If you want Tornado to leave the logging configuration alone so you can manage it yourself, either pass --logging=none on the command line or do the following to disable it in code:

from tornado.options import options, parse_command_line
options.logging = None
parse_command_line()

在 4.3 版更改: Dashes and underscores are fully interchangeable in option names; options can be defined, set, and read with any mix of the two. Dashes are typical for command-line usage while config files require underscores.

Global functions

tornado.options.define(name, default=None, type=None, help=None, metavar=None, multiple=False, group=None, callback=None)

Defines an option in the global namespace.

See .

tornado.options.options

Global options object. All defined options are available as attributes on this object.

tornado.options.parse_command_line(args=None, final=True)

Parses global options from the command line.

See .

tornado.options.parse_config_file(path, final=True)

Parses global options from a config file.

See .

tornado.options.print_help(file=sys.stderr)

Prints all the command line options to stderr (or another file).

See .

tornado.options.add_parse_callback(callback)

Adds a parse callback, to be invoked when option parsing is done.

See

exception tornado.options.Error

Exception raised by errors in the options module.

OptionParser class

class tornado.options.OptionParser

A collection of options, a dictionary with object-like access.

Normally accessed via static functions in the module, which reference a global instance.

add_parse_callback(callback)

Adds a parse callback, to be invoked when option parsing is done.

as_dict()

The names and values of all options.

3.1 新版功能.

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

Defines a new command line option.

If type is given (one of str, float, int, datetime, or timedelta) or can be inferred from the default, we parse the command line arguments based on the given type. If multiple is True, we accept comma-separated values, and the option value is always a list.

For multi-value integers, we also accept the syntax x:y, which turns into range(x, y) - very useful for long integer ranges.

help and metavar are used to construct the automatically generated command line help string. The help message is formatted like:

--name=METAVAR      help string

group is used to group the defined options in logical groups. By default, command line options are grouped by the file in which they are defined.

Command line option names must be unique globally. They can be parsed from the command line with or parsed from a config file with .

If a callback is given, it will be run with the new value whenever the option is changed. This can be used to combine command-line and file-based options:

define("config", type=str, help="path to config file",
       callback=lambda path: parse_config_file(path, final=False))

With this definition, options in the file specified by --config will override options set earlier on the command line, but can be overridden by later flags.

group_dict(group)

The names and values of options in a group.

Useful for copying options into Application settings:

from tornado.options import define, parse_command_line, options

define('template_path', group='application')
define('static_path', group='application')

parse_command_line()

application = Application(
    handlers, **options.group_dict('application'))

3.1 新版功能.

groups()

The set of option-groups created by define.

3.1 新版功能.

items()

A sequence of (name, value) pairs.

3.1 新版功能.

mockable()

Returns a wrapper around self that is compatible with .

The function (included in the standard library package since Python 3.3, or in the third-party mock package for older versions of Python) is incompatible with objects like options that override __getattr__ and __setattr__. This function returns an object that can be used with to modify option values:

with mock.patch.object(options.mockable(), 'name', value):
    assert options.name == value

parse_command_line(args=None, final=True)

Parses all options given on the command line (defaults to ).

Note that args[0] is ignored since it is the program name in .

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 configurations from multiple sources.

parse_config_file(path, final=True)

Parses and loads the Python config file at the given path.

If final is False, parse callbacks will not be run. This is useful for applications that wish to combine configurations from multiple sources.

在 4.1 版更改: Config files are now always interpreted as utf-8 instead of the system default encoding.

在 4.4 版更改: The special variable __file__ is available inside config files, specifying the absolute path to the config file itself.

print_help(file=None)

Prints all the command line options to stderr (or another file).