506 lines
19 KiB
Python
506 lines
19 KiB
Python
from __future__ import annotations
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import importlib.metadata
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import inspect
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import types
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import warnings
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from typing import Any
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from typing import Callable
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from typing import cast
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from typing import Final
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from typing import Iterable
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from typing import Mapping
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from typing import Sequence
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from . import _tracing
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from ._callers import _multicall
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from ._hooks import _HookImplFunction
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from ._hooks import _Namespace
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from ._hooks import _Plugin
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from ._hooks import _SubsetHookCaller
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from ._hooks import HookCaller
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from ._hooks import HookImpl
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from ._hooks import HookimplOpts
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from ._hooks import HookRelay
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from ._hooks import HookspecOpts
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from ._hooks import normalize_hookimpl_opts
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from ._result import Result
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_BeforeTrace = Callable[[str, Sequence[HookImpl], Mapping[str, Any]], None]
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_AfterTrace = Callable[[Result[Any], str, Sequence[HookImpl], Mapping[str, Any]], None]
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def _warn_for_function(warning: Warning, function: Callable[..., object]) -> None:
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func = cast(types.FunctionType, function)
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warnings.warn_explicit(
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warning,
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type(warning),
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lineno=func.__code__.co_firstlineno,
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filename=func.__code__.co_filename,
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)
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class PluginValidationError(Exception):
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"""Plugin failed validation.
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:param plugin: The plugin which failed validation.
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:param message: Error message.
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"""
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def __init__(self, plugin: _Plugin, message: str) -> None:
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super().__init__(message)
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#: The plugin which failed validation.
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self.plugin = plugin
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class DistFacade:
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"""Emulate a pkg_resources Distribution"""
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def __init__(self, dist: importlib.metadata.Distribution) -> None:
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self._dist = dist
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@property
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def project_name(self) -> str:
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name: str = self.metadata["name"]
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return name
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def __getattr__(self, attr: str, default=None):
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return getattr(self._dist, attr, default)
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def __dir__(self) -> list[str]:
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return sorted(dir(self._dist) + ["_dist", "project_name"])
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class PluginManager:
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"""Core class which manages registration of plugin objects and 1:N hook
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calling.
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You can register new hooks by calling :meth:`add_hookspecs(module_or_class)
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<PluginManager.add_hookspecs>`.
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You can register plugin objects (which contain hook implementations) by
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calling :meth:`register(plugin) <PluginManager.register>`.
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For debugging purposes you can call :meth:`PluginManager.enable_tracing`
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which will subsequently send debug information to the trace helper.
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:param project_name:
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The short project name. Prefer snake case. Make sure it's unique!
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"""
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def __init__(self, project_name: str) -> None:
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#: The project name.
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self.project_name: Final = project_name
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self._name2plugin: Final[dict[str, _Plugin]] = {}
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self._plugin_distinfo: Final[list[tuple[_Plugin, DistFacade]]] = []
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#: The "hook relay", used to call a hook on all registered plugins.
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#: See :ref:`calling`.
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self.hook: Final = HookRelay()
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#: The tracing entry point. See :ref:`tracing`.
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self.trace: Final[_tracing.TagTracerSub] = _tracing.TagTracer().get(
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"pluginmanage"
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)
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self._inner_hookexec = _multicall
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def _hookexec(
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self,
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hook_name: str,
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methods: Sequence[HookImpl],
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kwargs: Mapping[str, object],
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firstresult: bool,
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) -> object | list[object]:
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# called from all hookcaller instances.
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# enable_tracing will set its own wrapping function at self._inner_hookexec
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return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
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def register(self, plugin: _Plugin, name: str | None = None) -> str | None:
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"""Register a plugin and return its name.
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:param name:
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The name under which to register the plugin. If not specified, a
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name is generated using :func:`get_canonical_name`.
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:returns:
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The plugin name. If the name is blocked from registering, returns
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``None``.
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If the plugin is already registered, raises a :exc:`ValueError`.
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"""
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plugin_name = name or self.get_canonical_name(plugin)
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if plugin_name in self._name2plugin:
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if self._name2plugin.get(plugin_name, -1) is None:
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return None # blocked plugin, return None to indicate no registration
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raise ValueError(
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"Plugin name already registered: %s=%s\n%s"
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% (plugin_name, plugin, self._name2plugin)
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)
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if plugin in self._name2plugin.values():
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raise ValueError(
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"Plugin already registered under a different name: %s=%s\n%s"
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% (plugin_name, plugin, self._name2plugin)
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)
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# XXX if an error happens we should make sure no state has been
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# changed at point of return
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self._name2plugin[plugin_name] = plugin
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# register matching hook implementations of the plugin
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for name in dir(plugin):
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hookimpl_opts = self.parse_hookimpl_opts(plugin, name)
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if hookimpl_opts is not None:
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normalize_hookimpl_opts(hookimpl_opts)
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method: _HookImplFunction[object] = getattr(plugin, name)
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hookimpl = HookImpl(plugin, plugin_name, method, hookimpl_opts)
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name = hookimpl_opts.get("specname") or name
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hook: HookCaller | None = getattr(self.hook, name, None)
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if hook is None:
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hook = HookCaller(name, self._hookexec)
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setattr(self.hook, name, hook)
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elif hook.has_spec():
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self._verify_hook(hook, hookimpl)
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hook._maybe_apply_history(hookimpl)
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hook._add_hookimpl(hookimpl)
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return plugin_name
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def parse_hookimpl_opts(self, plugin: _Plugin, name: str) -> HookimplOpts | None:
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"""Try to obtain a hook implementation from an item with the given name
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in the given plugin which is being searched for hook impls.
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:returns:
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The parsed hookimpl options, or None to skip the given item.
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This method can be overridden by ``PluginManager`` subclasses to
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customize how hook implementation are picked up. By default, returns the
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options for items decorated with :class:`HookimplMarker`.
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"""
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method: object = getattr(plugin, name)
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if not inspect.isroutine(method):
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return None
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try:
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res: HookimplOpts | None = getattr(
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method, self.project_name + "_impl", None
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)
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except Exception:
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res = {} # type: ignore[assignment]
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if res is not None and not isinstance(res, dict):
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# false positive
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res = None # type:ignore[unreachable]
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return res
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def unregister(
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self, plugin: _Plugin | None = None, name: str | None = None
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) -> Any | None:
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"""Unregister a plugin and all of its hook implementations.
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The plugin can be specified either by the plugin object or the plugin
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name. If both are specified, they must agree.
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Returns the unregistered plugin, or ``None`` if not found.
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"""
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if name is None:
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assert plugin is not None, "one of name or plugin needs to be specified"
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name = self.get_name(plugin)
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assert name is not None, "plugin is not registered"
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if plugin is None:
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plugin = self.get_plugin(name)
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if plugin is None:
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return None
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hookcallers = self.get_hookcallers(plugin)
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if hookcallers:
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for hookcaller in hookcallers:
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hookcaller._remove_plugin(plugin)
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# if self._name2plugin[name] == None registration was blocked: ignore
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if self._name2plugin.get(name):
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assert name is not None
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del self._name2plugin[name]
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return plugin
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def set_blocked(self, name: str) -> None:
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"""Block registrations of the given name, unregister if already registered."""
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self.unregister(name=name)
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self._name2plugin[name] = None
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def is_blocked(self, name: str) -> bool:
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"""Return whether the given plugin name is blocked."""
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return name in self._name2plugin and self._name2plugin[name] is None
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def add_hookspecs(self, module_or_class: _Namespace) -> None:
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"""Add new hook specifications defined in the given ``module_or_class``.
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Functions are recognized as hook specifications if they have been
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decorated with a matching :class:`HookspecMarker`.
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"""
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names = []
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for name in dir(module_or_class):
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spec_opts = self.parse_hookspec_opts(module_or_class, name)
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if spec_opts is not None:
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hc: HookCaller | None = getattr(self.hook, name, None)
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if hc is None:
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hc = HookCaller(name, self._hookexec, module_or_class, spec_opts)
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setattr(self.hook, name, hc)
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else:
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# Plugins registered this hook without knowing the spec.
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hc.set_specification(module_or_class, spec_opts)
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for hookfunction in hc.get_hookimpls():
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self._verify_hook(hc, hookfunction)
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names.append(name)
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if not names:
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raise ValueError(
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f"did not find any {self.project_name!r} hooks in {module_or_class!r}"
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)
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def parse_hookspec_opts(
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self, module_or_class: _Namespace, name: str
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) -> HookspecOpts | None:
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"""Try to obtain a hook specification from an item with the given name
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in the given module or class which is being searched for hook specs.
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:returns:
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The parsed hookspec options for defining a hook, or None to skip the
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given item.
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This method can be overridden by ``PluginManager`` subclasses to
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customize how hook specifications are picked up. By default, returns the
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options for items decorated with :class:`HookspecMarker`.
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"""
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method = getattr(module_or_class, name)
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opts: HookspecOpts | None = getattr(method, self.project_name + "_spec", None)
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return opts
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def get_plugins(self) -> set[Any]:
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"""Return a set of all registered plugin objects."""
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return set(self._name2plugin.values())
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def is_registered(self, plugin: _Plugin) -> bool:
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"""Return whether the plugin is already registered."""
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return any(plugin == val for val in self._name2plugin.values())
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def get_canonical_name(self, plugin: _Plugin) -> str:
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"""Return a canonical name for a plugin object.
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Note that a plugin may be registered under a different name
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specified by the caller of :meth:`register(plugin, name) <register>`.
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To obtain the name of a registered plugin use :meth:`get_name(plugin)
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<get_name>` instead.
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"""
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name: str | None = getattr(plugin, "__name__", None)
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return name or str(id(plugin))
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def get_plugin(self, name: str) -> Any | None:
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"""Return the plugin registered under the given name, if any."""
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return self._name2plugin.get(name)
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def has_plugin(self, name: str) -> bool:
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"""Return whether a plugin with the given name is registered."""
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return self.get_plugin(name) is not None
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def get_name(self, plugin: _Plugin) -> str | None:
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"""Return the name the plugin is registered under, or ``None`` if
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is isn't."""
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for name, val in self._name2plugin.items():
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if plugin == val:
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return name
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return None
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def _verify_hook(self, hook: HookCaller, hookimpl: HookImpl) -> None:
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if hook.is_historic() and (hookimpl.hookwrapper or hookimpl.wrapper):
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raise PluginValidationError(
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hookimpl.plugin,
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"Plugin %r\nhook %r\nhistoric incompatible with yield/wrapper/hookwrapper"
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% (hookimpl.plugin_name, hook.name),
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)
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assert hook.spec is not None
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if hook.spec.warn_on_impl:
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_warn_for_function(hook.spec.warn_on_impl, hookimpl.function)
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# positional arg checking
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notinspec = set(hookimpl.argnames) - set(hook.spec.argnames)
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if notinspec:
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raise PluginValidationError(
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hookimpl.plugin,
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"Plugin %r for hook %r\nhookimpl definition: %s\n"
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"Argument(s) %s are declared in the hookimpl but "
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"can not be found in the hookspec"
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% (
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hookimpl.plugin_name,
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hook.name,
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_formatdef(hookimpl.function),
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notinspec,
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),
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)
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if (
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hookimpl.wrapper or hookimpl.hookwrapper
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) and not inspect.isgeneratorfunction(hookimpl.function):
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raise PluginValidationError(
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hookimpl.plugin,
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"Plugin %r for hook %r\nhookimpl definition: %s\n"
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"Declared as wrapper=True or hookwrapper=True "
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"but function is not a generator function"
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% (hookimpl.plugin_name, hook.name, _formatdef(hookimpl.function)),
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)
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if hookimpl.wrapper and hookimpl.hookwrapper:
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raise PluginValidationError(
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hookimpl.plugin,
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"Plugin %r for hook %r\nhookimpl definition: %s\n"
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"The wrapper=True and hookwrapper=True options are mutually exclusive"
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% (hookimpl.plugin_name, hook.name, _formatdef(hookimpl.function)),
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)
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def check_pending(self) -> None:
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"""Verify that all hooks which have not been verified against a
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hook specification are optional, otherwise raise
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:exc:`PluginValidationError`."""
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for name in self.hook.__dict__:
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if name[0] != "_":
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hook: HookCaller = getattr(self.hook, name)
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if not hook.has_spec():
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for hookimpl in hook.get_hookimpls():
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if not hookimpl.optionalhook:
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raise PluginValidationError(
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hookimpl.plugin,
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"unknown hook %r in plugin %r"
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% (name, hookimpl.plugin),
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)
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def load_setuptools_entrypoints(self, group: str, name: str | None = None) -> int:
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"""Load modules from querying the specified setuptools ``group``.
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:param group:
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Entry point group to load plugins.
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:param name:
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If given, loads only plugins with the given ``name``.
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:return:
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The number of plugins loaded by this call.
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"""
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count = 0
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for dist in list(importlib.metadata.distributions()):
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for ep in dist.entry_points:
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if (
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ep.group != group
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or (name is not None and ep.name != name)
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# already registered
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or self.get_plugin(ep.name)
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or self.is_blocked(ep.name)
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):
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continue
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plugin = ep.load()
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self.register(plugin, name=ep.name)
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self._plugin_distinfo.append((plugin, DistFacade(dist)))
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count += 1
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return count
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def list_plugin_distinfo(self) -> list[tuple[_Plugin, DistFacade]]:
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"""Return a list of (plugin, distinfo) pairs for all
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setuptools-registered plugins."""
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return list(self._plugin_distinfo)
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def list_name_plugin(self) -> list[tuple[str, _Plugin]]:
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"""Return a list of (name, plugin) pairs for all registered plugins."""
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return list(self._name2plugin.items())
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def get_hookcallers(self, plugin: _Plugin) -> list[HookCaller] | None:
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"""Get all hook callers for the specified plugin.
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:returns:
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The hook callers, or ``None`` if ``plugin`` is not registered in
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this plugin manager.
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"""
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if self.get_name(plugin) is None:
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return None
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hookcallers = []
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for hookcaller in self.hook.__dict__.values():
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for hookimpl in hookcaller.get_hookimpls():
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if hookimpl.plugin is plugin:
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hookcallers.append(hookcaller)
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return hookcallers
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def add_hookcall_monitoring(
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self, before: _BeforeTrace, after: _AfterTrace
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) -> Callable[[], None]:
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"""Add before/after tracing functions for all hooks.
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Returns an undo function which, when called, removes the added tracers.
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``before(hook_name, hook_impls, kwargs)`` will be called ahead
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of all hook calls and receive a hookcaller instance, a list
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of HookImpl instances and the keyword arguments for the hook call.
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``after(outcome, hook_name, hook_impls, kwargs)`` receives the
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same arguments as ``before`` but also a :class:`~pluggy.Result` object
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which represents the result of the overall hook call.
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"""
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oldcall = self._inner_hookexec
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def traced_hookexec(
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hook_name: str,
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hook_impls: Sequence[HookImpl],
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caller_kwargs: Mapping[str, object],
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firstresult: bool,
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) -> object | list[object]:
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before(hook_name, hook_impls, caller_kwargs)
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outcome = Result.from_call(
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lambda: oldcall(hook_name, hook_impls, caller_kwargs, firstresult)
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)
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after(outcome, hook_name, hook_impls, caller_kwargs)
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return outcome.get_result()
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self._inner_hookexec = traced_hookexec
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def undo() -> None:
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self._inner_hookexec = oldcall
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return undo
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def enable_tracing(self) -> Callable[[], None]:
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"""Enable tracing of hook calls.
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Returns an undo function which, when called, removes the added tracing.
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"""
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hooktrace = self.trace.root.get("hook")
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def before(
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hook_name: str, methods: Sequence[HookImpl], kwargs: Mapping[str, object]
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) -> None:
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hooktrace.root.indent += 1
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hooktrace(hook_name, kwargs)
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def after(
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outcome: Result[object],
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hook_name: str,
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methods: Sequence[HookImpl],
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kwargs: Mapping[str, object],
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) -> None:
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if outcome.exception is None:
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hooktrace("finish", hook_name, "-->", outcome.get_result())
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hooktrace.root.indent -= 1
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return self.add_hookcall_monitoring(before, after)
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def subset_hook_caller(
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self, name: str, remove_plugins: Iterable[_Plugin]
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) -> HookCaller:
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"""Return a proxy :class:`~pluggy.HookCaller` instance for the named
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method which manages calls to all registered plugins except the ones
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from remove_plugins."""
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orig: HookCaller = getattr(self.hook, name)
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plugins_to_remove = {plug for plug in remove_plugins if hasattr(plug, name)}
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if plugins_to_remove:
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return _SubsetHookCaller(orig, plugins_to_remove)
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return orig
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def _formatdef(func: Callable[..., object]) -> str:
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return f"{func.__name__}{inspect.signature(func)}"
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