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601 lines
22 KiB
Python
601 lines
22 KiB
Python
"""A base class for objects that are configurable."""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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from __future__ import annotations
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import logging
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import typing as t
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from copy import deepcopy
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from textwrap import dedent
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from traitlets.traitlets import (
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Any,
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Container,
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Dict,
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HasTraits,
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Instance,
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TraitType,
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default,
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observe,
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observe_compat,
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validate,
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)
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from traitlets.utils import warnings
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from traitlets.utils.bunch import Bunch
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from traitlets.utils.text import indent, wrap_paragraphs
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from .loader import Config, DeferredConfig, LazyConfigValue, _is_section_key
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# -----------------------------------------------------------------------------
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# Helper classes for Configurables
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# -----------------------------------------------------------------------------
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if t.TYPE_CHECKING:
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LoggerType = t.Union[logging.Logger, logging.LoggerAdapter[t.Any]]
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else:
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LoggerType = t.Any
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class ConfigurableError(Exception):
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pass
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class MultipleInstanceError(ConfigurableError):
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pass
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# -----------------------------------------------------------------------------
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# Configurable implementation
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# -----------------------------------------------------------------------------
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class Configurable(HasTraits):
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config = Instance(Config, (), {})
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parent = Instance("traitlets.config.configurable.Configurable", allow_none=True)
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def __init__(self, **kwargs: t.Any) -> None:
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"""Create a configurable given a config config.
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Parameters
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----------
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config : Config
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If this is empty, default values are used. If config is a
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:class:`Config` instance, it will be used to configure the
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instance.
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parent : Configurable instance, optional
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The parent Configurable instance of this object.
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Notes
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-----
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Subclasses of Configurable must call the :meth:`__init__` method of
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:class:`Configurable` *before* doing anything else and using
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:func:`super`::
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class MyConfigurable(Configurable):
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def __init__(self, config=None):
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super(MyConfigurable, self).__init__(config=config)
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# Then any other code you need to finish initialization.
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This ensures that instances will be configured properly.
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"""
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parent = kwargs.pop("parent", None)
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if parent is not None:
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# config is implied from parent
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if kwargs.get("config", None) is None:
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kwargs["config"] = parent.config
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self.parent = parent
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config = kwargs.pop("config", None)
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# load kwarg traits, other than config
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super().__init__(**kwargs)
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# record traits set by config
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config_override_names = set()
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def notice_config_override(change: Bunch) -> None:
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"""Record traits set by both config and kwargs.
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They will need to be overridden again after loading config.
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"""
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if change.name in kwargs:
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config_override_names.add(change.name)
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self.observe(notice_config_override)
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# load config
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if config is not None:
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# We used to deepcopy, but for now we are trying to just save
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# by reference. This *could* have side effects as all components
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# will share config. In fact, I did find such a side effect in
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# _config_changed below. If a config attribute value was a mutable type
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# all instances of a component were getting the same copy, effectively
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# making that a class attribute.
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# self.config = deepcopy(config)
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self.config = config
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else:
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# allow _config_default to return something
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self._load_config(self.config)
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self.unobserve(notice_config_override)
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for name in config_override_names:
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setattr(self, name, kwargs[name])
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# -------------------------------------------------------------------------
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# Static trait notifications
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# -------------------------------------------------------------------------
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@classmethod
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def section_names(cls) -> list[str]:
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"""return section names as a list"""
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return [
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c.__name__
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for c in reversed(cls.__mro__)
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if issubclass(c, Configurable) and issubclass(cls, c)
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]
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def _find_my_config(self, cfg: Config) -> t.Any:
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"""extract my config from a global Config object
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will construct a Config object of only the config values that apply to me
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based on my mro(), as well as those of my parent(s) if they exist.
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If I am Bar and my parent is Foo, and their parent is Tim,
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this will return merge following config sections, in this order::
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[Bar, Foo.Bar, Tim.Foo.Bar]
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With the last item being the highest priority.
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"""
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cfgs = [cfg]
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if self.parent:
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cfgs.append(self.parent._find_my_config(cfg))
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my_config = Config()
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for c in cfgs:
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for sname in self.section_names():
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# Don't do a blind getattr as that would cause the config to
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# dynamically create the section with name Class.__name__.
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if c._has_section(sname):
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my_config.merge(c[sname])
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return my_config
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def _load_config(
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self,
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cfg: Config,
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section_names: list[str] | None = None,
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traits: dict[str, TraitType[t.Any, t.Any]] | None = None,
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) -> None:
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"""load traits from a Config object"""
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if traits is None:
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traits = self.traits(config=True)
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if section_names is None:
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section_names = self.section_names()
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my_config = self._find_my_config(cfg)
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# hold trait notifications until after all config has been loaded
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with self.hold_trait_notifications():
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for name, config_value in my_config.items():
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if name in traits:
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if isinstance(config_value, LazyConfigValue):
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# ConfigValue is a wrapper for using append / update on containers
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# without having to copy the initial value
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initial = getattr(self, name)
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config_value = config_value.get_value(initial)
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elif isinstance(config_value, DeferredConfig):
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# DeferredConfig tends to come from CLI/environment variables
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config_value = config_value.get_value(traits[name])
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# We have to do a deepcopy here if we don't deepcopy the entire
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# config object. If we don't, a mutable config_value will be
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# shared by all instances, effectively making it a class attribute.
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setattr(self, name, deepcopy(config_value))
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elif not _is_section_key(name) and not isinstance(config_value, Config):
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from difflib import get_close_matches
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if isinstance(self, LoggingConfigurable):
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assert self.log is not None
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warn = self.log.warning
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else:
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def warn(msg: t.Any) -> None:
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return warnings.warn(msg, UserWarning, stacklevel=9)
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matches = get_close_matches(name, traits)
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msg = f"Config option `{name}` not recognized by `{self.__class__.__name__}`."
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if len(matches) == 1:
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msg += f" Did you mean `{matches[0]}`?"
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elif len(matches) >= 1:
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msg += " Did you mean one of: `{matches}`?".format(
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matches=", ".join(sorted(matches))
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)
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warn(msg)
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@observe("config")
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@observe_compat
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def _config_changed(self, change: Bunch) -> None:
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"""Update all the class traits having ``config=True`` in metadata.
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For any class trait with a ``config`` metadata attribute that is
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``True``, we update the trait with the value of the corresponding
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config entry.
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"""
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# Get all traits with a config metadata entry that is True
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traits = self.traits(config=True)
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# We auto-load config section for this class as well as any parent
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# classes that are Configurable subclasses. This starts with Configurable
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# and works down the mro loading the config for each section.
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section_names = self.section_names()
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self._load_config(change.new, traits=traits, section_names=section_names)
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def update_config(self, config: Config) -> None:
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"""Update config and load the new values"""
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# traitlets prior to 4.2 created a copy of self.config in order to trigger change events.
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# Some projects (IPython < 5) relied upon one side effect of this,
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# that self.config prior to update_config was not modified in-place.
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# For backward-compatibility, we must ensure that self.config
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# is a new object and not modified in-place,
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# but config consumers should not rely on this behavior.
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self.config = deepcopy(self.config)
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# load config
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self._load_config(config)
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# merge it into self.config
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self.config.merge(config)
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# TODO: trigger change event if/when dict-update change events take place
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# DO NOT trigger full trait-change
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@classmethod
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def class_get_help(cls, inst: HasTraits | None = None) -> str:
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"""Get the help string for this class in ReST format.
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If `inst` is given, its current trait values will be used in place of
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class defaults.
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"""
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assert inst is None or isinstance(inst, cls)
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final_help = []
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base_classes = ", ".join(p.__name__ for p in cls.__bases__)
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final_help.append(f"{cls.__name__}({base_classes}) options")
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final_help.append(len(final_help[0]) * "-")
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for _, v in sorted(cls.class_traits(config=True).items()):
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help = cls.class_get_trait_help(v, inst)
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final_help.append(help)
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return "\n".join(final_help)
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@classmethod
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def class_get_trait_help(
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cls,
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trait: TraitType[t.Any, t.Any],
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inst: HasTraits | None = None,
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helptext: str | None = None,
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) -> str:
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"""Get the helptext string for a single trait.
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:param inst:
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If given, its current trait values will be used in place of
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the class default.
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:param helptext:
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If not given, uses the `help` attribute of the current trait.
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"""
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assert inst is None or isinstance(inst, cls)
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lines = []
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header = f"--{cls.__name__}.{trait.name}"
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if isinstance(trait, (Container, Dict)):
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multiplicity = trait.metadata.get("multiplicity", "append")
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if isinstance(trait, Dict):
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sample_value = "<key-1>=<value-1>"
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else:
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sample_value = "<%s-item-1>" % trait.__class__.__name__.lower()
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if multiplicity == "append":
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header = f"{header}={sample_value}..."
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else:
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header = f"{header} {sample_value}..."
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else:
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header = f"{header}=<{trait.__class__.__name__}>"
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# header = "--%s.%s=<%s>" % (cls.__name__, trait.name, trait.__class__.__name__)
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lines.append(header)
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if helptext is None:
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helptext = trait.help
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if helptext != "":
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helptext = "\n".join(wrap_paragraphs(helptext, 76))
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lines.append(indent(helptext))
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if "Enum" in trait.__class__.__name__:
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# include Enum choices
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lines.append(indent("Choices: %s" % trait.info()))
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if inst is not None:
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lines.append(indent(f"Current: {getattr(inst, trait.name or '')!r}"))
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else:
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try:
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dvr = trait.default_value_repr()
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except Exception:
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dvr = None # ignore defaults we can't construct
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if dvr is not None:
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if len(dvr) > 64:
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dvr = dvr[:61] + "..."
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lines.append(indent("Default: %s" % dvr))
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return "\n".join(lines)
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@classmethod
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def class_print_help(cls, inst: HasTraits | None = None) -> None:
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"""Get the help string for a single trait and print it."""
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print(cls.class_get_help(inst)) # noqa: T201
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@classmethod
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def _defining_class(
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cls, trait: TraitType[t.Any, t.Any], classes: t.Sequence[type[HasTraits]]
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) -> type[Configurable]:
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"""Get the class that defines a trait
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For reducing redundant help output in config files.
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Returns the current class if:
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- the trait is defined on this class, or
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- the class where it is defined would not be in the config file
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Parameters
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----------
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trait : Trait
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The trait to look for
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classes : list
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The list of other classes to consider for redundancy.
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Will return `cls` even if it is not defined on `cls`
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if the defining class is not in `classes`.
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"""
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defining_cls = cls
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assert trait.name is not None
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for parent in cls.mro():
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if (
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issubclass(parent, Configurable)
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and parent in classes
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and parent.class_own_traits(config=True).get(trait.name, None) is trait
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):
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defining_cls = parent
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return defining_cls
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@classmethod
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def class_config_section(cls, classes: t.Sequence[type[HasTraits]] | None = None) -> str:
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"""Get the config section for this class.
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Parameters
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----------
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classes : list, optional
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The list of other classes in the config file.
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Used to reduce redundant information.
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"""
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def c(s: str) -> str:
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"""return a commented, wrapped block."""
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s = "\n\n".join(wrap_paragraphs(s, 78))
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return "## " + s.replace("\n", "\n# ")
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# section header
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breaker = "#" + "-" * 78
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parent_classes = ", ".join(p.__name__ for p in cls.__bases__ if issubclass(p, Configurable))
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s = f"# {cls.__name__}({parent_classes}) configuration"
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lines = [breaker, s, breaker]
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# get the description trait
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desc = cls.class_traits().get("description")
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if desc:
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desc = desc.default_value
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if not desc:
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# no description from trait, use __doc__
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desc = getattr(cls, "__doc__", "") # type:ignore[arg-type]
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if desc:
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lines.append(c(desc)) # type:ignore[arg-type]
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lines.append("")
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for name, trait in sorted(cls.class_traits(config=True).items()):
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default_repr = trait.default_value_repr()
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if classes:
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defining_class = cls._defining_class(trait, classes)
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else:
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defining_class = cls
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if defining_class is cls:
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# cls owns the trait, show full help
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if trait.help:
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lines.append(c(trait.help))
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if "Enum" in type(trait).__name__:
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# include Enum choices
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lines.append("# Choices: %s" % trait.info())
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lines.append("# Default: %s" % default_repr)
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else:
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# Trait appears multiple times and isn't defined here.
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# Truncate help to first line + "See also Original.trait"
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if trait.help:
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lines.append(c(trait.help.split("\n", 1)[0]))
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lines.append(f"# See also: {defining_class.__name__}.{name}")
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lines.append(f"# c.{cls.__name__}.{name} = {default_repr}")
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lines.append("")
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return "\n".join(lines)
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@classmethod
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def class_config_rst_doc(cls) -> str:
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"""Generate rST documentation for this class' config options.
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Excludes traits defined on parent classes.
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"""
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lines = []
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classname = cls.__name__
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for _, trait in sorted(cls.class_traits(config=True).items()):
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ttype = trait.__class__.__name__
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if not trait.name:
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continue
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termline = classname + "." + trait.name
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# Choices or type
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if "Enum" in ttype:
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# include Enum choices
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termline += " : " + trait.info_rst() # type:ignore[attr-defined]
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else:
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termline += " : " + ttype
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lines.append(termline)
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# Default value
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try:
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dvr = trait.default_value_repr()
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except Exception:
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dvr = None # ignore defaults we can't construct
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if dvr is not None:
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if len(dvr) > 64:
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dvr = dvr[:61] + "..."
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# Double up backslashes, so they get to the rendered docs
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dvr = dvr.replace("\\n", "\\\\n")
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lines.append(indent("Default: ``%s``" % dvr))
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lines.append("")
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help = trait.help or "No description"
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lines.append(indent(dedent(help)))
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# Blank line
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lines.append("")
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return "\n".join(lines)
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class LoggingConfigurable(Configurable):
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"""A parent class for Configurables that log.
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Subclasses have a log trait, and the default behavior
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is to get the logger from the currently running Application.
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"""
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log = Any(help="Logger or LoggerAdapter instance", allow_none=False)
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@validate("log")
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def _validate_log(self, proposal: Bunch) -> LoggerType:
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if not isinstance(proposal.value, (logging.Logger, logging.LoggerAdapter)):
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# warn about unsupported type, but be lenient to allow for duck typing
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warnings.warn(
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f"{self.__class__.__name__}.log should be a Logger or LoggerAdapter,"
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f" got {proposal.value}.",
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UserWarning,
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stacklevel=2,
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)
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return t.cast(LoggerType, proposal.value)
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@default("log")
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def _log_default(self) -> LoggerType:
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if isinstance(self.parent, LoggingConfigurable):
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assert self.parent is not None
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return t.cast(logging.Logger, self.parent.log)
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from traitlets import log
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return log.get_logger()
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def _get_log_handler(self) -> logging.Handler | None:
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"""Return the default Handler
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Returns None if none can be found
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Deprecated, this now returns the first log handler which may or may
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not be the default one.
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"""
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if not self.log:
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return None
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logger: logging.Logger = (
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self.log if isinstance(self.log, logging.Logger) else self.log.logger
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)
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if not getattr(logger, "handlers", None):
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# no handlers attribute or empty handlers list
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return None
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return logger.handlers[0]
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CT = t.TypeVar("CT", bound="SingletonConfigurable")
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class SingletonConfigurable(LoggingConfigurable):
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"""A configurable that only allows one instance.
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This class is for classes that should only have one instance of itself
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or *any* subclass. To create and retrieve such a class use the
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:meth:`SingletonConfigurable.instance` method.
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"""
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_instance = None
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@classmethod
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def _walk_mro(cls) -> t.Generator[type[SingletonConfigurable], None, None]:
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"""Walk the cls.mro() for parent classes that are also singletons
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|
|
|
For use in instance()
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"""
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|
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for subclass in cls.mro():
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if (
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issubclass(cls, subclass)
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and issubclass(subclass, SingletonConfigurable)
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and subclass != SingletonConfigurable
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):
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yield subclass
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|
@classmethod
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|
def clear_instance(cls) -> None:
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|
"""unset _instance for this class and singleton parents."""
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|
if not cls.initialized():
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|
return
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|
for subclass in cls._walk_mro():
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|
if isinstance(subclass._instance, cls):
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|
# only clear instances that are instances
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|
# of the calling class
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|
subclass._instance = None # type:ignore[unreachable]
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|
|
|
@classmethod
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|
def instance(cls: type[CT], *args: t.Any, **kwargs: t.Any) -> CT:
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|
"""Returns a global instance of this class.
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|
|
|
This method create a new instance if none have previously been created
|
|
and returns a previously created instance is one already exists.
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|
|
|
The arguments and keyword arguments passed to this method are passed
|
|
on to the :meth:`__init__` method of the class upon instantiation.
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|
|
|
Examples
|
|
--------
|
|
Create a singleton class using instance, and retrieve it::
|
|
|
|
>>> from traitlets.config.configurable import SingletonConfigurable
|
|
>>> class Foo(SingletonConfigurable): pass
|
|
>>> foo = Foo.instance()
|
|
>>> foo == Foo.instance()
|
|
True
|
|
|
|
Create a subclass that is retrieved using the base class instance::
|
|
|
|
>>> class Bar(SingletonConfigurable): pass
|
|
>>> class Bam(Bar): pass
|
|
>>> bam = Bam.instance()
|
|
>>> bam == Bar.instance()
|
|
True
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|
"""
|
|
# Create and save the instance
|
|
if cls._instance is None:
|
|
inst = cls(*args, **kwargs)
|
|
# Now make sure that the instance will also be returned by
|
|
# parent classes' _instance attribute.
|
|
for subclass in cls._walk_mro():
|
|
subclass._instance = inst
|
|
|
|
if isinstance(cls._instance, cls):
|
|
return cls._instance
|
|
else:
|
|
raise MultipleInstanceError(
|
|
f"An incompatible sibling of '{cls.__name__}' is already instantiated"
|
|
f" as singleton: {type(cls._instance).__name__}"
|
|
)
|
|
|
|
@classmethod
|
|
def initialized(cls) -> bool:
|
|
"""Has an instance been created?"""
|
|
return hasattr(cls, "_instance") and cls._instance is not None
|