Source code for tornado.options

# Copyright 2009 Facebook
# 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
# 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.

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

This module is inspired by Google's `gflags
<>`_. The primary difference
with libraries such as `argparse` is that a global registry is used so
that options may be defined in any module (it also enables
`tornado.log` by default). The rest of Tornado does not depend on this
module, so feel free to use `argparse` or other configuration
libraries if you prefer them.

Options must be defined with `tornado.options.define` before use,
generally at the top level of a module. The options are then
accessible as attributes of `tornado.options.options`::

    # myapp/
    from tornado.options import define, options

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

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

    # myapp/
    from tornado.options import define, options

    define("port", default=8080, help="port to listen on")

    def start_server():
        app = make_app()

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 `parse_command_line` or `parse_config_file`::

    import myapp.db, myapp.server
    import tornado.options

    if __name__ == '__main__':
        # or

.. note::

   When using multiple ``parse_*`` functions, pass ``final=False`` to all
   but the last one, or side effects may occur twice (in particular,
   this can result in log messages being doubled).

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

.. note::

   By default, several options are defined that will configure the
   standard `logging` module when `parse_command_line` or `parse_config_file`
   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

.. versionchanged:: 4.3
   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

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

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

import typing
from typing import Any, Iterator, Iterable, Tuple, Set, Dict, Callable, List, TextIO

if typing.TYPE_CHECKING:
    from typing import Optional  # noqa: F401

[docs]class Error(Exception): """Exception raised by errors in the options module.""" pass
[docs]class OptionParser(object): """A collection of options, a dictionary with object-like access. Normally accessed via static functions in the `tornado.options` module, which reference a global instance. """ def __init__(self) -> None: # we have to use self.__dict__ because we override setattr. self.__dict__["_options"] = {} self.__dict__["_parse_callbacks"] = [] self.define( "help", type=bool, help="show this help information", callback=self._help_callback, ) def _normalize_name(self, name: str) -> str: return name.replace("_", "-") def __getattr__(self, name: str) -> Any: name = self._normalize_name(name) if isinstance(self._options.get(name), _Option): return self._options[name].value() raise AttributeError("Unrecognized option %r" % name) def __setattr__(self, name: str, value: Any) -> None: name = self._normalize_name(name) if isinstance(self._options.get(name), _Option): return self._options[name].set(value) raise AttributeError("Unrecognized option %r" % name) def __iter__(self) -> Iterator: return ( for opt in self._options.values()) def __contains__(self, name: str) -> bool: name = self._normalize_name(name) return name in self._options def __getitem__(self, name: str) -> Any: return self.__getattr__(name) def __setitem__(self, name: str, value: Any) -> None: return self.__setattr__(name, value)
[docs] def items(self) -> Iterable[Tuple[str, Any]]: """An iterable of (name, value) pairs. .. versionadded:: 3.1 """ return [(, opt.value()) for name, opt in self._options.items()]
[docs] def groups(self) -> Set[str]: """The set of option-groups created by ``define``. .. versionadded:: 3.1 """ return set(opt.group_name for opt in self._options.values())
[docs] def group_dict(self, group: str) -> Dict[str, Any]: """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')) .. versionadded:: 3.1 """ return dict( (, opt.value()) for name, opt in self._options.items() if not group or group == opt.group_name )
[docs] def as_dict(self) -> Dict[str, Any]: """The names and values of all options. .. versionadded:: 3.1 """ return dict((, opt.value()) for name, opt in self._options.items())
[docs] def define( self, name: str, default: Any = None, type: type = None, help: str = None, metavar: str = None, multiple: bool = False, group: str = None, callback: Callable[[Any], None] = None, ) -> None: """Defines a new command line option. ``type`` can be any of `str`, `int`, `float`, `bool`, `~datetime.datetime`, or `~datetime.timedelta`. If no ``type`` is given but a ``default`` is, ``type`` is the type of ``default``. Otherwise, ``type`` defaults to `str`. If ``multiple`` is True, the option value is a list of ``type`` instead of an instance of ``type``. ``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. 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. """ normalized = self._normalize_name(name) if normalized in self._options: raise Error( "Option %r already defined in %s" % (normalized, self._options[normalized].file_name) ) frame = sys._getframe(0) options_file = frame.f_code.co_filename # Can be called directly, or through top level define() fn, in which # case, step up above that frame to look for real caller. if ( frame.f_back.f_code.co_filename == options_file and frame.f_back.f_code.co_name == "define" ): frame = frame.f_back file_name = frame.f_back.f_code.co_filename if file_name == options_file: file_name = "" if type is None: if not multiple and default is not None: type = default.__class__ else: type = str if group: group_name = group # type: Optional[str] else: group_name = file_name option = _Option( name, file_name=file_name, default=default, type=type, help=help, metavar=metavar, multiple=multiple, group_name=group_name, callback=callback, ) self._options[normalized] = option
[docs] def parse_command_line( self, args: List[str] = None, final: bool = True ) -> List[str]: """Parses all options given on the command line (defaults to `sys.argv`). Options look like ``--option=value`` and are parsed according to their ``type``. For boolean options, ``--option`` is equivalent to ``--option=true`` If the option has ``multiple=True``, comma-separated values are accepted. For multi-value integer options, the syntax ``x:y`` is also accepted and equivalent to ``range(x, y)``. Note that ``args[0]`` is ignored since it is the program name in `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 configurations from multiple sources. """ if args is None: args = sys.argv remaining = [] # type: List[str] 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
[docs] def parse_config_file(self, path: str, final: bool = True) -> None: """Parses and loads the config file at the given path. The config file contains Python code that will be executed (so it is **not safe** to use untrusted config files). Anything in the global namespace that matches a defined option will be used to set that option's value. Options may either be the specified type for the option or strings (in which case they will be parsed the same way as in `.parse_command_line`) Example (using the options defined in the top-level docs of this module):: port = 80 mysql_host = '' # Both lists and comma-separated strings are allowed for # multiple=True. memcache_hosts = ['', ''] memcache_hosts = ',' If ``final`` is ``False``, parse callbacks will not be run. This is useful for applications that wish to combine configurations from multiple sources. .. note:: `tornado.options` is primarily a command-line library. Config file support is provided for applications that wish to use it, but applications that prefer config files may wish to look at other libraries instead. .. versionchanged:: 4.1 Config files are now always interpreted as utf-8 instead of the system default encoding. .. versionchanged:: 4.4 The special variable ``__file__`` is available inside config files, specifying the absolute path to the config file itself. .. versionchanged:: 5.1 Added the ability to set options via strings in config files. """ config = {"__file__": os.path.abspath(path)} with open(path, "rb") as f: exec_in(native_str(, config, config) for name in config: normalized = self._normalize_name(name) if normalized in self._options: option = self._options[normalized] if option.multiple: if not isinstance(config[name], (list, str)): raise Error( "Option %r is required to be a list of %s " "or a comma-separated string" % (, option.type.__name__) ) if type(config[name]) == str and option.type != str: option.parse(config[name]) else: option.set(config[name]) if final: self.run_parse_callbacks()
[docs] def print_help(self, file: TextIO = None) -> None: """Prints all the command line options to stderr (or another file).""" if file is None: file = sys.stderr print("Usage: %s [OPTIONS]" % sys.argv[0], file=file) print("\nOptions:\n", file=file) by_group = {} # type: Dict[str, List[_Option]] for option in self._options.values(): by_group.setdefault(option.group_name, []).append(option) for filename, o in sorted(by_group.items()): if filename: print("\n%s options:\n" % os.path.normpath(filename), file=file) o.sort(key=lambda option: for option in o: # Always print names with dashes in a CLI context. prefix = self._normalize_name( if option.metavar: prefix += "=" + option.metavar description = or "" if option.default is not None and option.default != "": description += " (default %s)" % option.default lines = textwrap.wrap(description, 79 - 35) if len(prefix) > 30 or len(lines) == 0: lines.insert(0, "") print(" --%-30s %s" % (prefix, lines[0]), file=file) for line in lines[1:]: print("%-34s %s" % (" ", line), file=file) print(file=file)
def _help_callback(self, value: bool) -> None: if value: self.print_help() sys.exit(0)
[docs] def add_parse_callback(self, callback: Callable[[], None]) -> None: """Adds a parse callback, to be invoked when option parsing is done.""" self._parse_callbacks.append(callback)
def run_parse_callbacks(self) -> None: for callback in self._parse_callbacks: callback()
[docs] def mockable(self) -> "_Mockable": """Returns a wrapper around self that is compatible with `mock.patch <unittest.mock.patch>`. The `mock.patch <unittest.mock.patch>` function (included in the standard library `unittest.mock` 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 `mock.patch.object <unittest.mock.patch.object>` to modify option values:: with mock.patch.object(options.mockable(), 'name', value): assert == value """ return _Mockable(self)
class _Mockable(object): """`mock.patch` compatible wrapper for `OptionParser`. As of ``mock`` version 1.0.1, when an object uses ``__getattr__`` hooks instead of ``__dict__``, ``patch.__exit__`` tries to delete the attribute it set instead of setting a new one (assuming that the object does not catpure ``__setattr__``, so the patch created a new attribute in ``__dict__``). _Mockable's getattr and setattr pass through to the underlying OptionParser, and delattr undoes the effect of a previous setattr. """ def __init__(self, options: OptionParser) -> None: # Modify __dict__ directly to bypass __setattr__ self.__dict__["_options"] = options self.__dict__["_originals"] = {} def __getattr__(self, name: str) -> Any: return getattr(self._options, name) def __setattr__(self, name: str, value: Any) -> None: assert name not in self._originals, "don't reuse mockable objects" self._originals[name] = getattr(self._options, name) setattr(self._options, name, value) def __delattr__(self, name: str) -> None: setattr(self._options, name, self._originals.pop(name)) class _Option(object): # This class could almost be made generic, but the way the types # interact with the multiple argument makes this tricky. (default # and the callback use List[T], but type is still Type[T]). UNSET = object() def __init__( self, name: str, default: Any = None, type: type = None, help: str = None, metavar: str = None, multiple: bool = False, file_name: str = None, group_name: str = None, callback: Callable[[Any], None] = None, ) -> None: if default is None and multiple: default = [] = name if type is None: raise ValueError("type must not be None") self.type = type = help self.metavar = metavar self.multiple = multiple self.file_name = file_name self.group_name = group_name self.callback = callback self.default = default self._value = _Option.UNSET # type: Any def value(self) -> Any: return self.default if self._value is _Option.UNSET else self._value def parse(self, value: str) -> Any: _parse = { datetime.datetime: self._parse_datetime, datetime.timedelta: self._parse_timedelta, bool: self._parse_bool, basestring_type: self._parse_string, }.get( self.type, self.type ) # type: Callable[[str], Any] if self.multiple: self._value = [] for part in value.split(","): if issubclass(self.type, numbers.Integral): # allow ranges of the form X:Y (inclusive at both ends) lo_str, _, hi_str = part.partition(":") lo = _parse(lo_str) hi = _parse(hi_str) if hi_str else lo self._value.extend(range(lo, hi + 1)) else: self._value.append(_parse(part)) else: self._value = _parse(value) if self.callback is not None: self.callback(self._value) return self.value() def set(self, value: Any) -> None: if self.multiple: if not isinstance(value, list): raise Error( "Option %r is required to be a list of %s" % (, self.type.__name__) ) for item in value: if item is not None and not isinstance(item, self.type): raise Error( "Option %r is required to be a list of %s" % (, self.type.__name__) ) else: if value is not None and not isinstance(value, self.type): raise Error( "Option %r is required to be a %s (%s given)" % (, self.type.__name__, type(value)) ) self._value = value if self.callback is not None: self.callback(self._value) # Supported date/time formats in our options _DATETIME_FORMATS = [ "%a %b %d %H:%M:%S %Y", "%Y-%m-%d %H:%M:%S", "%Y-%m-%d %H:%M", "%Y-%m-%dT%H:%M", "%Y%m%d %H:%M:%S", "%Y%m%d %H:%M", "%Y-%m-%d", "%Y%m%d", "%H:%M:%S", "%H:%M", ] def _parse_datetime(self, value: str) -> datetime.datetime: for format in self._DATETIME_FORMATS: try: return datetime.datetime.strptime(value, format) except ValueError: pass raise Error("Unrecognized date/time format: %r" % value) _TIMEDELTA_ABBREV_DICT = { "h": "hours", "m": "minutes", "min": "minutes", "s": "seconds", "sec": "seconds", "ms": "milliseconds", "us": "microseconds", "d": "days", "w": "weeks", } _FLOAT_PATTERN = r"[-+]?(?:\d+(?:\.\d*)?|\.\d+)(?:[eE][-+]?\d+)?" _TIMEDELTA_PATTERN = re.compile( r"\s*(%s)\s*(\w*)\s*" % _FLOAT_PATTERN, re.IGNORECASE ) def _parse_timedelta(self, value: str) -> datetime.timedelta: try: sum = datetime.timedelta() start = 0 while start < len(value): m = self._TIMEDELTA_PATTERN.match(value, start) if not m: raise Exception() num = float( units = or "seconds" units = self._TIMEDELTA_ABBREV_DICT.get(units, units) sum += datetime.timedelta(**{units: num}) start = m.end() return sum except Exception: raise def _parse_bool(self, value: str) -> bool: return value.lower() not in ("false", "0", "f") def _parse_string(self, value: str) -> str: return _unicode(value) options = OptionParser() """Global options object. All defined options are available as attributes on this object. """
[docs]def define( name: str, default: Any = None, type: type = None, help: str = None, metavar: str = None, multiple: bool = False, group: str = None, callback: Callable[[Any], None] = None, ) -> None: """Defines an option in the global namespace. See `OptionParser.define`. """ return options.define( name, default=default, type=type, help=help, metavar=metavar, multiple=multiple, group=group, callback=callback, )
[docs]def parse_command_line(args: List[str] = None, final: bool = True) -> List[str]: """Parses global options from the command line. See `OptionParser.parse_command_line`. """ return options.parse_command_line(args, final=final)
[docs]def parse_config_file(path: str, final: bool = True) -> None: """Parses global options from a config file. See `OptionParser.parse_config_file`. """ return options.parse_config_file(path, final=final)
[docs]def add_parse_callback(callback: Callable[[], None]) -> None: """Adds a parse callback, to be invoked when option parsing is done. See `OptionParser.add_parse_callback` """ options.add_parse_callback(callback)
# Default options define_logging_options(options)