290 lines
9.8 KiB
Python
290 lines
9.8 KiB
Python
from __future__ import annotations
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import sys
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from functools import partial
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from importlib.metadata import entry_points
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from typing import TYPE_CHECKING, Any, Callable, Generic, TypeVar, cast
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from altair.utils.deprecation import deprecated_warn
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if sys.version_info >= (3, 13):
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from typing import TypeIs
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else:
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from typing_extensions import TypeIs
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if sys.version_info >= (3, 12):
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from typing import TypeAliasType
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else:
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from typing_extensions import TypeAliasType
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if TYPE_CHECKING:
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from types import TracebackType
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T = TypeVar("T")
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R = TypeVar("R")
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Plugin = TypeAliasType("Plugin", Callable[..., R], type_params=(R,))
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PluginT = TypeVar("PluginT", bound=Plugin[Any])
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IsPlugin = Callable[[object], TypeIs[Plugin[Any]]]
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def _is_type(tp: type[T], /) -> Callable[[object], TypeIs[type[T]]]:
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"""
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Converts a type to guard function.
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Added for compatibility with original `PluginRegistry` default.
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"""
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def func(obj: object, /) -> TypeIs[type[T]]:
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return isinstance(obj, tp)
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return func
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class NoSuchEntryPoint(Exception):
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def __init__(self, group, name):
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self.group = group
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self.name = name
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def __str__(self):
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return f"No {self.name!r} entry point found in group {self.group!r}"
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class PluginEnabler(Generic[PluginT, R]):
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"""
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Context manager for enabling plugins.
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This object lets you use enable() as a context manager to
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temporarily enable a given plugin::
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with plugins.enable("name"):
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do_something() # 'name' plugin temporarily enabled
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# plugins back to original state
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"""
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def __init__(
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self, registry: PluginRegistry[PluginT, R], name: str, **options: Any
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) -> None:
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self.registry: PluginRegistry[PluginT, R] = registry
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self.name: str = name
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self.options: dict[str, Any] = options
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self.original_state: dict[str, Any] = registry._get_state()
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self.registry._enable(name, **options)
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def __enter__(self) -> PluginEnabler[PluginT, R]:
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return self
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def __exit__(self, typ: type, value: Exception, traceback: TracebackType) -> None:
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self.registry._set_state(self.original_state)
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def __repr__(self) -> str:
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return f"{type(self.registry).__name__}.enable({self.name!r})"
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class PluginRegistry(Generic[PluginT, R]):
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"""
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A registry for plugins.
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This is a plugin registry that allows plugins to be loaded/registered
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in two ways:
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1. Through an explicit call to ``.register(name, value)``.
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2. By looking for other Python packages that are installed and provide
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a setuptools entry point group.
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When you create an instance of this class, provide the name of the
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entry point group to use::
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reg = PluginRegister("my_entrypoint_group")
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"""
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# this is a mapping of name to error message to allow custom error messages
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# in case an entrypoint is not found
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entrypoint_err_messages: dict[str, str] = {}
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# global settings is a key-value mapping of settings that are stored globally
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# in the registry rather than passed to the plugins
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_global_settings: dict[str, Any] = {}
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def __init__(
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self, entry_point_group: str = "", plugin_type: IsPlugin = callable
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) -> None:
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"""
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Create a PluginRegistry for a named entry point group.
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Parameters
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----------
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entry_point_group: str
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The name of the entry point group.
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plugin_type
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A type narrowing function that will optionally be used for runtime
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type checking loaded plugins.
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References
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----------
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https://typing.readthedocs.io/en/latest/spec/narrowing.html
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"""
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self.entry_point_group: str = entry_point_group
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self.plugin_type: IsPlugin
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if plugin_type is not callable and isinstance(plugin_type, type):
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msg: Any = (
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f"Pass a callable `TypeIs` function to `plugin_type` instead.\n"
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f"{type(self).__name__!r}(plugin_type)\n\n"
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f"See also:\n"
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f"https://typing.readthedocs.io/en/latest/spec/narrowing.html\n"
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f"https://docs.astral.sh/ruff/rules/assert/"
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)
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deprecated_warn(msg, version="5.4.0")
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self.plugin_type = cast(IsPlugin, _is_type(plugin_type))
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else:
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self.plugin_type = plugin_type
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self._active: Plugin[R] | None = None
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self._active_name: str = ""
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self._plugins: dict[str, PluginT] = {}
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self._options: dict[str, Any] = {}
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self._global_settings: dict[str, Any] = self.__class__._global_settings.copy()
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def register(self, name: str, value: PluginT | None) -> PluginT | None:
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"""
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Register a plugin by name and value.
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This method is used for explicit registration of a plugin and shouldn't be
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used to manage entry point managed plugins, which are auto-loaded.
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Parameters
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----------
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name: str
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The name of the plugin.
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value: PluginType or None
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The actual plugin object to register or None to unregister that plugin.
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Returns
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-------
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plugin: PluginType or None
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The plugin that was registered or unregistered.
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"""
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if value is None:
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return self._plugins.pop(name, None)
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elif self.plugin_type(value):
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self._plugins[name] = value
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return value
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else:
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msg = f"{type(value).__name__!r} is not compatible with {type(self).__name__!r}"
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raise TypeError(msg)
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def names(self) -> list[str]:
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"""List the names of the registered and entry points plugins."""
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exts = list(self._plugins.keys())
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e_points = importlib_metadata_get(self.entry_point_group)
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more_exts = [ep.name for ep in e_points]
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exts.extend(more_exts)
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return sorted(set(exts))
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def _get_state(self) -> dict[str, Any]:
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"""Return a dictionary representing the current state of the registry."""
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return {
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"_active": self._active,
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"_active_name": self._active_name,
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"_plugins": self._plugins.copy(),
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"_options": self._options.copy(),
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"_global_settings": self._global_settings.copy(),
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}
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def _set_state(self, state: dict[str, Any]) -> None:
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"""Reset the state of the registry."""
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assert set(state.keys()) == {
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"_active",
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"_active_name",
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"_plugins",
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"_options",
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"_global_settings",
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}
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for key, val in state.items():
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setattr(self, key, val)
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def _enable(self, name: str, **options) -> None:
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if name not in self._plugins:
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try:
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(ep,) = (
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ep
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for ep in importlib_metadata_get(self.entry_point_group)
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if ep.name == name
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)
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except ValueError as err:
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if name in self.entrypoint_err_messages:
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raise ValueError(self.entrypoint_err_messages[name]) from err
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else:
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raise NoSuchEntryPoint(self.entry_point_group, name) from err
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value = cast(PluginT, ep.load())
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self.register(name, value)
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self._active_name = name
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self._active = self._plugins[name]
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for key in set(options.keys()) & set(self._global_settings.keys()):
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self._global_settings[key] = options.pop(key)
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self._options = options
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def enable(
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self, name: str | None = None, **options: Any
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) -> PluginEnabler[PluginT, R]:
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"""
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Enable a plugin by name.
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This can be either called directly, or used as a context manager.
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Parameters
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----------
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name : string (optional)
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The name of the plugin to enable. If not specified, then use the
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current active name.
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**options :
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Any additional parameters will be passed to the plugin as keyword
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arguments
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Returns
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-------
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PluginEnabler:
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An object that allows enable() to be used as a context manager
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"""
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if name is None:
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name = self.active
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return PluginEnabler(self, name, **options)
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@property
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def active(self) -> str:
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"""Return the name of the currently active plugin."""
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return self._active_name
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@property
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def options(self) -> dict[str, Any]:
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"""Return the current options dictionary."""
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return self._options
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def get(self) -> partial[R] | Plugin[R] | None:
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"""Return the currently active plugin."""
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if (func := self._active) and self.plugin_type(func):
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return partial(func, **self._options) if self._options else func
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elif self._active is not None:
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msg = (
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f"{type(self).__name__!r} requires all plugins to be callable objects, "
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f"but {type(self._active).__name__!r} is not callable."
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)
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raise TypeError(msg)
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elif TYPE_CHECKING:
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# NOTE: The `None` return is implicit, but `mypy` isn't satisfied
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# - `ruff` will factor out explicit `None` return
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# - `pyright` has no issue
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raise NotImplementedError
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def __repr__(self) -> str:
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return f"{type(self).__name__}(active={self.active!r}, registered={self.names()!r})"
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def importlib_metadata_get(group):
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ep = entry_points()
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# 'select' was introduced in Python 3.10 and 'get' got deprecated
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# We don't check for Python version here as by checking with hasattr we
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# also get compatibility with the importlib_metadata package which had a different
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# deprecation cycle for 'get'
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if hasattr(ep, "select"):
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return ep.select(group=group) # pyright: ignore
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else:
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return ep.get(group, [])
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