# encoding: utf-8
"""A base class for a configurable application."""
# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.
from __future__ import print_function
from copy import deepcopy
import json
import logging
import os
import re
import sys
from collections import defaultdict, OrderedDict
from decorator import decorator
from traitlets.config.configurable import Configurable, SingletonConfigurable
from traitlets.config.loader import (
KVArgParseConfigLoader, PyFileConfigLoader, Config, ArgumentError, ConfigFileNotFound, JSONFileConfigLoader
)
from traitlets.traitlets import (
Bool, Unicode, List, Enum, Dict, Instance, TraitError, observe, observe_compat, default,
)
from ipython_genutils.importstring import import_item
from ipython_genutils.text import indent, wrap_paragraphs, dedent
from ipython_genutils import py3compat
import six
#-----------------------------------------------------------------------------
# Descriptions for the various sections
#-----------------------------------------------------------------------------
# merge flags&aliases into options
option_description = """
Arguments that take values are actually convenience aliases to full
Configurables, whose aliases are listed on the help line. For more information
on full configurables, see '--help-all'.
""".strip() # trim newlines of front and back
keyvalue_description = """
Parameters are set from command-line arguments of the form:
`--Class.trait=value`.
This line is evaluated in Python, so simple expressions are allowed, e.g.::
`--C.a='range(3)'` For setting C.a=[0,1,2].
""".strip() # trim newlines of front and back
# sys.argv can be missing, for example when python is embedded. See the docs
# for details: http://docs.python.org/2/c-api/intro.html#embedding-python
if not hasattr(sys, "argv"):
sys.argv = [""]
subcommand_description = """
Subcommands are launched as `{app} cmd [args]`. For information on using
subcommand 'cmd', do: `{app} cmd -h`.
"""
# get running program name
#-----------------------------------------------------------------------------
# Application class
#-----------------------------------------------------------------------------
_envvar = os.environ.get('TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR','')
if _envvar.lower() in {'1','true'}:
TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR = True
elif _envvar.lower() in {'0','false',''} :
TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR = False
else:
raise ValueError("Unsupported value for environment variable: 'TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR' is set to '%s' which is none of {'0', '1', 'false', 'true', ''}."% _envvar )
@decorator
def catch_config_error(method, app, *args, **kwargs):
"""Method decorator for catching invalid config (Trait/ArgumentErrors) during init.
On a TraitError (generally caused by bad config), this will print the trait's
message, and exit the app.
For use on init methods, to prevent invoking excepthook on invalid input.
"""
try:
return method(app, *args, **kwargs)
except (TraitError, ArgumentError) as e:
app.print_help()
app.log.fatal("Bad config encountered during initialization:")
app.log.fatal(str(e))
app.log.debug("Config at the time: %s", app.config)
app.exit(1)
class ApplicationError(Exception):
pass
class LevelFormatter(logging.Formatter):
"""Formatter with additional `highlevel` record
This field is empty if log level is less than highlevel_limit,
otherwise it is formatted with self.highlevel_format.
Useful for adding 'WARNING' to warning messages,
without adding 'INFO' to info, etc.
"""
highlevel_limit = logging.WARN
highlevel_format = " %(levelname)s |"
def format(self, record):
if record.levelno >= self.highlevel_limit:
record.highlevel = self.highlevel_format % record.__dict__
else:
record.highlevel = ""
return super(LevelFormatter, self).format(record)
class Application(SingletonConfigurable):
"""A singleton application with full configuration support."""
# The name of the application, will usually match the name of the command
# line application
name = Unicode(u'application')
# The description of the application that is printed at the beginning
# of the help.
description = Unicode(u'This is an application.')
# default section descriptions
option_description = Unicode(option_description)
keyvalue_description = Unicode(keyvalue_description)
subcommand_description = Unicode(subcommand_description)
python_config_loader_class = PyFileConfigLoader
json_config_loader_class = JSONFileConfigLoader
# The usage and example string that goes at the end of the help string.
examples = Unicode()
# A sequence of Configurable subclasses whose config=True attributes will
# be exposed at the command line.
classes = []
def _classes_inc_parents(self):
"""Iterate through configurable classes, including configurable parents
Children should always be after parents, and each class should only be
yielded once.
"""
seen = set()
for c in self.classes:
# We want to sort parents before children, so we reverse the MRO
for parent in reversed(c.mro()):
if issubclass(parent, Configurable) and (parent not in seen):
seen.add(parent)
yield parent
# The version string of this application.
version = Unicode(u'0.0')
# the argv used to initialize the application
argv = List()
# Whether failing to load config files should prevent startup
raise_config_file_errors = Bool(TRAITLETS_APPLICATION_RAISE_CONFIG_FILE_ERROR)
# The log level for the application
log_level = Enum((0,10,20,30,40,50,'DEBUG','INFO','WARN','ERROR','CRITICAL'),
default_value=logging.WARN,
help="Set the log level by value or name.").tag(config=True)
@observe('log_level')
@observe_compat
def _log_level_changed(self, change):
"""Adjust the log level when log_level is set."""
new = change.new
if isinstance(new, six.string_types):
new = getattr(logging, new)
self.log_level = new
self.log.setLevel(new)
_log_formatter_cls = LevelFormatter
log_datefmt = Unicode("%Y-%m-%d %H:%M:%S",
help="The date format used by logging formatters for %(asctime)s"
).tag(config=True)
log_format = Unicode("[%(name)s]%(highlevel)s %(message)s",
help="The Logging format template",
).tag(config=True)
@observe('log_datefmt', 'log_format')
@observe_compat
def _log_format_changed(self, change):
"""Change the log formatter when log_format is set."""
_log_handler = self.log.handlers[0]
_log_formatter = self._log_formatter_cls(fmt=self.log_format, datefmt=self.log_datefmt)
_log_handler.setFormatter(_log_formatter)
@default('log')
def _log_default(self):
"""Start logging for this application.
The default is to log to stderr using a StreamHandler, if no default
handler already exists. The log level starts at logging.WARN, but this
can be adjusted by setting the ``log_level`` attribute.
"""
log = logging.getLogger(self.__class__.__name__)
log.setLevel(self.log_level)
log.propagate = False
_log = log # copied from Logger.hasHandlers() (new in Python 3.2)
while _log:
if _log.handlers:
return log
if not _log.propagate:
break
else:
_log = _log.parent
if sys.executable and sys.executable.endswith('pythonw.exe'):
# this should really go to a file, but file-logging is only
# hooked up in parallel applications
_log_handler = logging.StreamHandler(open(os.devnull, 'w'))
else:
_log_handler = logging.StreamHandler()
_log_formatter = self._log_formatter_cls(fmt=self.log_format, datefmt=self.log_datefmt)
_log_handler.setFormatter(_log_formatter)
log.addHandler(_log_handler)
return log
# the alias map for configurables
aliases = Dict({'log-level' : 'Application.log_level'})
# flags for loading Configurables or store_const style flags
# flags are loaded from this dict by '--key' flags
# this must be a dict of two-tuples, the first element being the Config/dict
# and the second being the help string for the flag
flags = Dict()
@observe('flags')
@observe_compat
def _flags_changed(self, change):
"""ensure flags dict is valid"""
new = change.new
for key, value in new.items():
assert len(value) == 2, "Bad flag: %r:%s" % (key, value)
assert isinstance(value[0], (dict, Config)), "Bad flag: %r:%s" % (key, value)
assert isinstance(value[1], six.string_types), "Bad flag: %r:%s" % (key, value)
# subcommands for launching other applications
# if this is not empty, this will be a parent Application
# this must be a dict of two-tuples,
# the first element being the application class/import string
# and the second being the help string for the subcommand
subcommands = Dict()
# parse_command_line will initialize a subapp, if requested
subapp = Instance('traitlets.config.application.Application', allow_none=True)
# extra command-line arguments that don't set config values
extra_args = List(Unicode())
cli_config = Instance(Config, (), {},
help="""The subset of our configuration that came from the command-line
We re-load this configuration after loading config files,
to ensure that it maintains highest priority.
"""
)
_loaded_config_files = List()
def __init__(self, **kwargs):
SingletonConfigurable.__init__(self, **kwargs)
# Ensure my class is in self.classes, so my attributes appear in command line
# options and config files.
cls = self.__class__
if cls not in self.classes:
if self.classes is cls.classes:
# class attr, assign instead of insert
cls.classes = [cls] + self.classes
else:
self.classes.insert(0, self.__class__)
@observe('config')
@observe_compat
def _config_changed(self, change):
super(Application, self)._config_changed(change)
self.log.debug('Config changed:')
self.log.debug(repr(change.new))
@catch_config_error
def initialize(self, argv=None):
"""Do the basic steps to configure me.
Override in subclasses.
"""
self.parse_command_line(argv)
def start(self):
"""Start the app mainloop.
Override in subclasses.
"""
if self.subapp is not None:
return self.subapp.start()
def print_alias_help(self):
"""Print the alias part of the help."""
if not self.aliases:
return
lines = []
classdict = {}
for cls in self.classes:
# include all parents (up to, but excluding Configurable) in available names
for c in cls.mro()[:-3]:
classdict[c.__name__] = c
for alias, longname in self.aliases.items():
classname, traitname = longname.split('.',1)
cls = classdict[classname]
trait = cls.class_traits(config=True)[traitname]
help = cls.class_get_trait_help(trait).splitlines()
# reformat first line
help[0] = help[0].replace(longname, alias) + ' (%s)'%longname
if len(alias) == 1:
help[0] = help[0].replace('--%s='%alias, '-%s '%alias)
lines.extend(help)
# lines.append('')
print(os.linesep.join(lines))
def print_flag_help(self):
"""Print the flag part of the help."""
if not self.flags:
return
lines = []
for m, (cfg,help) in self.flags.items():
prefix = '--' if len(m) > 1 else '-'
lines.append(prefix+m)
lines.append(indent(dedent(help.strip())))
# lines.append('')
print(os.linesep.join(lines))
def print_options(self):
if not self.flags and not self.aliases:
return
lines = ['Options']
lines.append('-'*len(lines[0]))
lines.append('')
for p in wrap_paragraphs(self.option_description):
lines.append(p)
lines.append('')
print(os.linesep.join(lines))
self.print_flag_help()
self.print_alias_help()
print()
def print_subcommands(self):
"""Print the subcommand part of the help."""
if not self.subcommands:
return
lines = ["Subcommands"]
lines.append('-'*len(lines[0]))
lines.append('')
for p in wrap_paragraphs(self.subcommand_description.format(
app=self.name)):
lines.append(p)
lines.append('')
for subc, (cls, help) in self.subcommands.items():
lines.append(subc)
if help:
lines.append(indent(dedent(help.strip())))
lines.append('')
print(os.linesep.join(lines))
def print_help(self, classes=False):
"""Print the help for each Configurable class in self.classes.
If classes=False (the default), only flags and aliases are printed.
"""
self.print_description()
self.print_subcommands()
self.print_options()
if classes:
help_classes = self.classes
if help_classes:
print("Class parameters")
print("----------------")
print()
for p in wrap_paragraphs(self.keyvalue_description):
print(p)
print()
for cls in help_classes:
cls.class_print_help()
print()
else:
print("To see all available configurables, use `--help-all`")
print()
self.print_examples()
def document_config_options(self):
"""Generate rST format documentation for the config options this application
Returns a multiline string.
"""
return '\n'.join(c.class_config_rst_doc()
for c in self._classes_inc_parents())
def print_description(self):
"""Print the application description."""
for p in wrap_paragraphs(self.description):
print(p)
print()
def print_examples(self):
"""Print usage and examples.
This usage string goes at the end of the command line help string
and should contain examples of the application's usage.
"""
if self.examples:
print("Examples")
print("--------")
print()
print(indent(dedent(self.examples.strip())))
print()
def print_version(self):
"""Print the version string."""
print(self.version)
@catch_config_error
def initialize_subcommand(self, subc, argv=None):
"""Initialize a subcommand with argv."""
subapp,help = self.subcommands.get(subc)
if isinstance(subapp, six.string_types):
subapp = import_item(subapp)
# clear existing instances
self.__class__.clear_instance()
# instantiate
self.subapp = subapp.instance(parent=self)
# and initialize subapp
self.subapp.initialize(argv)
def flatten_flags(self):
"""flatten flags and aliases, so cl-args override as expected.
This prevents issues such as an alias pointing to InteractiveShell,
but a config file setting the same trait in TerminalInteraciveShell
getting inappropriate priority over the command-line arg.
Only aliases with exactly one descendent in the class list
will be promoted.
"""
# build a tree of classes in our list that inherit from a particular
# it will be a dict by parent classname of classes in our list
# that are descendents
mro_tree = defaultdict(list)
for cls in self.classes:
clsname = cls.__name__
for parent in cls.mro()[1:-3]:
# exclude cls itself and Configurable,HasTraits,object
mro_tree[parent.__name__].append(clsname)
# flatten aliases, which have the form:
# { 'alias' : 'Class.trait' }
aliases = {}
for alias, cls_trait in self.aliases.items():
cls,trait = cls_trait.split('.',1)
children = mro_tree[cls]
if len(children) == 1:
# exactly one descendent, promote alias
cls = children[0]
aliases[alias] = '.'.join([cls,trait])
# flatten flags, which are of the form:
# { 'key' : ({'Cls' : {'trait' : value}}, 'help')}
flags = {}
for key, (flagdict, help) in self.flags.items():
newflag = {}
for cls, subdict in flagdict.items():
children = mro_tree[cls]
# exactly one descendent, promote flag section
if len(children) == 1:
cls = children[0]
newflag[cls] = subdict
flags[key] = (newflag, help)
return flags, aliases
@catch_config_error
def parse_command_line(self, argv=None):
"""Parse the command line arguments."""
argv = sys.argv[1:] if argv is None else argv
self.argv = [ py3compat.cast_unicode(arg) for arg in argv ]
if argv and argv[0] == 'help':
# turn `ipython help notebook` into `ipython notebook -h`
argv = argv[1:] + ['-h']
if self.subcommands and len(argv) > 0:
# we have subcommands, and one may have been specified
subc, subargv = argv[0], argv[1:]
if re.match(r'^\w(\-?\w)*$', subc) and subc in self.subcommands:
# it's a subcommand, and *not* a flag or class parameter
return self.initialize_subcommand(subc, subargv)
# Arguments after a '--' argument are for the script IPython may be
# about to run, not IPython iteslf. For arguments parsed here (help and
# version), we want to only search the arguments up to the first
# occurrence of '--', which we're calling interpreted_argv.
try:
interpreted_argv = argv[:argv.index('--')]
except ValueError:
interpreted_argv = argv
if any(x in interpreted_argv for x in ('-h', '--help-all', '--help')):
self.print_help('--help-all' in interpreted_argv)
self.exit(0)
if '--version' in interpreted_argv or '-V' in interpreted_argv:
self.print_version()
self.exit(0)
# flatten flags&aliases, so cl-args get appropriate priority:
flags,aliases = self.flatten_flags()
loader = KVArgParseConfigLoader(argv=argv, aliases=aliases,
flags=flags, log=self.log)
self.cli_config = deepcopy(loader.load_config())
self.update_config(self.cli_config)
# store unparsed args in extra_args
self.extra_args = loader.extra_args
@classmethod
def _load_config_files(cls, basefilename, path=None, log=None, raise_config_file_errors=False):
"""Load config files (py,json) by filename and path.
yield each config object in turn.
"""
if not isinstance(path, list):
path = [path]
for path in path[::-1]:
# path list is in descending priority order, so load files backwards:
pyloader = cls.python_config_loader_class(basefilename+'.py', path=path, log=log)
if log:
log.debug("Looking for %s in %s", basefilename, path or os.getcwd())
jsonloader = cls.json_config_loader_class(basefilename+'.json', path=path, log=log)
loaded = []
filenames = []
for loader in [pyloader, jsonloader]:
config = None
try:
config = loader.load_config()
except ConfigFileNotFound:
pass
except Exception:
# try to get the full filename, but it will be empty in the
# unlikely event that the error raised before filefind finished
filename = loader.full_filename or basefilename
# problem while running the file
if raise_config_file_errors:
raise
if log:
log.error("Exception while loading config file %s",
filename, exc_info=True)
else:
if log:
log.debug("Loaded config file: %s", loader.full_filename)
if config:
for filename, earlier_config in zip(filenames, loaded):
collisions = earlier_config.collisions(config)
if collisions and log:
log.warning("Collisions detected in {0} and {1} config files."
" {1} has higher priority: {2}".format(
filename, loader.full_filename, json.dumps(collisions, indent=2),
))
yield (config, loader.full_filename)
loaded.append(config)
filenames.append(loader.full_filename)
@property
def loaded_config_files(self):
"""Currently loaded configuration files"""
return self._loaded_config_files[:]
@catch_config_error
def load_config_file(self, filename, path=None):
"""Load config files by filename and path."""
filename, ext = os.path.splitext(filename)
new_config = Config()
for (config, filename) in self._load_config_files(filename, path=path, log=self.log,
raise_config_file_errors=self.raise_config_file_errors,
):
new_config.merge(config)
if filename not in self._loaded_config_files: # only add to list of loaded files if not previously loaded
self._loaded_config_files.append(filename)
# add self.cli_config to preserve CLI config priority
new_config.merge(self.cli_config)
self.update_config(new_config)
def _classes_in_config_sample(self):
"""
Yields only classes with own traits, and their subclasses.
Thus, produced sample config-file will contain all classes
on which a trait-value may be overridden:
- either on the class owning the trait,
- or on its subclasses, even if those subclasses do not define
any traits themselves.
"""
cls_to_config = OrderedDict( (cls, bool(cls.class_own_traits(config=True)))
for cls
in self._classes_inc_parents())
def is_any_parent_included(cls):
return any(b in cls_to_config and cls_to_config[b] for b in cls.__bases__)
## Mark "empty" classes for inclusion if their parents own-traits,
# and loop until no more classes gets marked.
#
while True:
to_incl_orig = cls_to_config.copy()
cls_to_config = OrderedDict( (cls, inc_yes or is_any_parent_included(cls))
for cls, inc_yes
in cls_to_config.items())
if cls_to_config == to_incl_orig:
break
for cl, inc_yes in cls_to_config.items():
if inc_yes:
yield cl
def generate_config_file(self):
"""generate default config file from Configurables"""
lines = ["# Configuration file for %s." % self.name]
lines.append('')
for cls in self._classes_in_config_sample():
lines.append(cls.class_config_section())
return '\n'.join(lines)
def exit(self, exit_status=0):
self.log.debug("Exiting application: %s" % self.name)
sys.exit(exit_status)
@classmethod
def launch_instance(cls, argv=None, **kwargs):
"""Launch a global instance of this Application
If a global instance already exists, this reinitializes and starts it
"""
app = cls.instance(**kwargs)
app.initialize(argv)
app.start()
#-----------------------------------------------------------------------------
# utility functions, for convenience
#-----------------------------------------------------------------------------
def boolean_flag(name, configurable, set_help='', unset_help=''):
"""Helper for building basic --trait, --no-trait flags.
Parameters
----------
name : str
The name of the flag.
configurable : str
The 'Class.trait' string of the trait to be set/unset with the flag
set_help : unicode
help string for --name flag
unset_help : unicode
help string for --no-name flag
Returns
-------
cfg : dict
A dict with two keys: 'name', and 'no-name', for setting and unsetting
the trait, respectively.
"""
# default helpstrings
set_help = set_help or "set %s=True"%configurable
unset_help = unset_help or "set %s=False"%configurable
cls,trait = configurable.split('.')
setter = {cls : {trait : True}}
unsetter = {cls : {trait : False}}
return {name : (setter, set_help), 'no-'+name : (unsetter, unset_help)}
def get_config():
"""Get the config object for the global Application instance, if there is one
otherwise return an empty config object
"""
if Application.initialized():
return Application.instance().config
else:
return Config()