Source code for pluggy.manager

import inspect
from . import _tracing
from .hooks import HookImpl, _HookRelay, _HookCaller, normalize_hookimpl_opts
import warnings

import importlib_metadata

def _warn_for_function(warning, function):

class PluginValidationError(Exception):
    """ plugin failed validation.

    :param object plugin: the plugin which failed validation,
        may be a module or an arbitrary object.

    def __init__(self, plugin, message):
        self.plugin = plugin
        super(Exception, self).__init__(message)

class DistFacade(object):
    """Emulate a pkg_resources Distribution"""

    def __init__(self, dist):
        self._dist = dist

    def project_name(self):
        return self.metadata["name"]

    def __getattr__(self, attr, default=None):
        return getattr(self._dist, attr, default)

    def __dir__(self):
        return sorted(dir(self._dist) + ["_dist", "project_name"])

[docs]class PluginManager(object): """ Core Pluginmanager class which manages registration of plugin objects and 1:N hook calling. You can register new hooks by calling ``add_hookspecs(module_or_class)``. You can register plugin objects (which contain hooks) by calling ``register(plugin)``. The Pluginmanager is initialized with a prefix that is searched for in the names of the dict of registered plugin objects. For debugging purposes you can call ``enable_tracing()`` which will subsequently send debug information to the trace helper. """ def __init__(self, project_name, implprefix=None): """If ``implprefix`` is given implementation functions will be recognized if their name matches the implprefix. """ self.project_name = project_name self._name2plugin = {} self._plugin2hookcallers = {} self._plugin_distinfo = [] self.trace = _tracing.TagTracer().get("pluginmanage") self.hook = _HookRelay(self.trace.root.get("hook")) if implprefix is not None: warnings.warn( "Support for the `implprefix` arg is now deprecated and will " "be removed in an upcoming release. Please use HookimplMarker.", DeprecationWarning, stacklevel=2, ) self._implprefix = implprefix self._inner_hookexec = lambda hook, methods, kwargs: hook.multicall( methods, kwargs, firstresult=hook.spec.opts.get("firstresult") if hook.spec else False, ) def _hookexec(self, hook, methods, kwargs): # called from all hookcaller instances. # enable_tracing will set its own wrapping function at self._inner_hookexec return self._inner_hookexec(hook, methods, kwargs)
[docs] def register(self, plugin, name=None): """ Register a plugin and return its canonical name or None if the name is blocked from registering. Raise a ValueError if the plugin is already registered. """ plugin_name = name or self.get_canonical_name(plugin) if plugin_name in self._name2plugin or plugin in self._plugin2hookcallers: if self._name2plugin.get(plugin_name, -1) is None: return # blocked plugin, return None to indicate no registration raise ValueError( "Plugin already registered: %s=%s\n%s" % (plugin_name, plugin, self._name2plugin) ) # XXX if an error happens we should make sure no state has been # changed at point of return self._name2plugin[plugin_name] = plugin # register matching hook implementations of the plugin self._plugin2hookcallers[plugin] = hookcallers = [] for name in dir(plugin): hookimpl_opts = self.parse_hookimpl_opts(plugin, name) if hookimpl_opts is not None: normalize_hookimpl_opts(hookimpl_opts) method = getattr(plugin, name) hookimpl = HookImpl(plugin, plugin_name, method, hookimpl_opts) hook = getattr(self.hook, name, None) if hook is None: hook = _HookCaller(name, self._hookexec) setattr(self.hook, name, hook) elif hook.has_spec(): self._verify_hook(hook, hookimpl) hook._maybe_apply_history(hookimpl) hook._add_hookimpl(hookimpl) hookcallers.append(hook) return plugin_name
def parse_hookimpl_opts(self, plugin, name): method = getattr(plugin, name) if not inspect.isroutine(method): return try: res = getattr(method, self.project_name + "_impl", None) except Exception: res = {} if res is not None and not isinstance(res, dict): # false positive res = None # TODO: remove when we drop implprefix in 1.0 elif res is None and self._implprefix and name.startswith(self._implprefix): _warn_for_function( DeprecationWarning( "The `implprefix` system is deprecated please decorate " "this function using an instance of HookimplMarker." ), method, ) res = {} return res
[docs] def unregister(self, plugin=None, name=None): """ unregister a plugin object and all its contained hook implementations from internal data structures. """ if name is None: assert plugin is not None, "one of name or plugin needs to be specified" name = self.get_name(plugin) if plugin is None: plugin = self.get_plugin(name) # if self._name2plugin[name] == None registration was blocked: ignore if self._name2plugin.get(name): del self._name2plugin[name] for hookcaller in self._plugin2hookcallers.pop(plugin, []): hookcaller._remove_plugin(plugin) return plugin
[docs] def set_blocked(self, name): """ block registrations of the given name, unregister if already registered. """ self.unregister(name=name) self._name2plugin[name] = None
[docs] def is_blocked(self, name): """ return True if the given plugin name is blocked. """ return name in self._name2plugin and self._name2plugin[name] is None
[docs] def add_hookspecs(self, module_or_class): """ add new hook specifications defined in the given module_or_class. Functions are recognized if they have been decorated accordingly. """ names = [] for name in dir(module_or_class): spec_opts = self.parse_hookspec_opts(module_or_class, name) if spec_opts is not None: hc = getattr(self.hook, name, None) if hc is None: hc = _HookCaller(name, self._hookexec, module_or_class, spec_opts) setattr(self.hook, name, hc) else: # plugins registered this hook without knowing the spec hc.set_specification(module_or_class, spec_opts) for hookfunction in hc.get_hookimpls(): self._verify_hook(hc, hookfunction) names.append(name) if not names: raise ValueError( "did not find any %r hooks in %r" % (self.project_name, module_or_class) )
def parse_hookspec_opts(self, module_or_class, name): method = getattr(module_or_class, name) return getattr(method, self.project_name + "_spec", None)
[docs] def get_plugins(self): """ return the set of registered plugins. """ return set(self._plugin2hookcallers)
[docs] def is_registered(self, plugin): """ Return True if the plugin is already registered. """ return plugin in self._plugin2hookcallers
[docs] def get_canonical_name(self, plugin): """ Return canonical name for a plugin object. Note that a plugin may be registered under a different name which was specified by the caller of register(plugin, name). To obtain the name of an registered plugin use ``get_name(plugin)`` instead.""" return getattr(plugin, "__name__", None) or str(id(plugin))
[docs] def get_plugin(self, name): """ Return a plugin or None for the given name. """ return self._name2plugin.get(name)
[docs] def has_plugin(self, name): """ Return True if a plugin with the given name is registered. """ return self.get_plugin(name) is not None
[docs] def get_name(self, plugin): """ Return name for registered plugin or None if not registered. """ for name, val in self._name2plugin.items(): if plugin == val: return name
def _verify_hook(self, hook, hookimpl): if hook.is_historic() and hookimpl.hookwrapper: raise PluginValidationError( hookimpl.plugin, "Plugin %r\nhook %r\nhistoric incompatible to hookwrapper" % (hookimpl.plugin_name,, ) if hook.spec.warn_on_impl: _warn_for_function(hook.spec.warn_on_impl, hookimpl.function) # positional arg checking notinspec = set(hookimpl.argnames) - set(hook.spec.argnames) if notinspec: raise PluginValidationError( hookimpl.plugin, "Plugin %r for hook %r\nhookimpl definition: %s\n" "Argument(s) %s are declared in the hookimpl but " "can not be found in the hookspec" % ( hookimpl.plugin_name,, _formatdef(hookimpl.function), notinspec, ), )
[docs] def check_pending(self): """ Verify that all hooks which have not been verified against a hook specification are optional, otherwise raise PluginValidationError""" for name in self.hook.__dict__: if name[0] != "_": hook = getattr(self.hook, name) if not hook.has_spec(): for hookimpl in hook.get_hookimpls(): if not hookimpl.optionalhook: raise PluginValidationError( hookimpl.plugin, "unknown hook %r in plugin %r" % (name, hookimpl.plugin), )
[docs] def load_setuptools_entrypoints(self, group, name=None): """ Load modules from querying the specified setuptools ``group``. :param str group: entry point group to load plugins :param str name: if given, loads only plugins with the given ``name``. :rtype: int :return: return the number of loaded plugins by this call. """ count = 0 for dist in importlib_metadata.distributions(): for ep in dist.entry_points: if ( != group or (name is not None and != name) # already registered or self.get_plugin( or self.is_blocked( ): continue plugin = ep.load() self.register(plugin, self._plugin_distinfo.append((plugin, DistFacade(dist))) count += 1 return count
[docs] def list_plugin_distinfo(self): """ return list of distinfo/plugin tuples for all setuptools registered plugins. """ return list(self._plugin_distinfo)
[docs] def list_name_plugin(self): """ return list of name/plugin pairs. """ return list(self._name2plugin.items())
[docs] def get_hookcallers(self, plugin): """ get all hook callers for the specified plugin. """ return self._plugin2hookcallers.get(plugin)
[docs] def add_hookcall_monitoring(self, before, after): """ add before/after tracing functions for all hooks and return an undo function which, when called, will remove the added tracers. ``before(hook_name, hook_impls, kwargs)`` will be called ahead of all hook calls and receive a hookcaller instance, a list of HookImpl instances and the keyword arguments for the hook call. ``after(outcome, hook_name, hook_impls, kwargs)`` receives the same arguments as ``before`` but also a :py:class:`_Result`` object which represents the result of the overall hook call. """ return _tracing._TracedHookExecution(self, before, after).undo
[docs] def enable_tracing(self): """ enable tracing of hook calls and return an undo function. """ hooktrace = self.hook._trace def before(hook_name, methods, kwargs): hooktrace.root.indent += 1 hooktrace(hook_name, kwargs) def after(outcome, hook_name, methods, kwargs): if outcome.excinfo is None: hooktrace("finish", hook_name, "-->", outcome.get_result()) hooktrace.root.indent -= 1 return self.add_hookcall_monitoring(before, after)
[docs] def subset_hook_caller(self, name, remove_plugins): """ Return a new _HookCaller instance for the named method which manages calls to all registered plugins except the ones from remove_plugins. """ orig = getattr(self.hook, name) plugins_to_remove = [plug for plug in remove_plugins if hasattr(plug, name)] if plugins_to_remove: hc = _HookCaller(, orig._hookexec, orig.spec.namespace, orig.spec.opts ) for hookimpl in orig.get_hookimpls(): plugin = hookimpl.plugin if plugin not in plugins_to_remove: hc._add_hookimpl(hookimpl) # we also keep track of this hook caller so it # gets properly removed on plugin unregistration self._plugin2hookcallers.setdefault(plugin, []).append(hc) return hc return orig
if hasattr(inspect, "signature"): def _formatdef(func): return "%s%s" % (func.__name__, str(inspect.signature(func))) else: def _formatdef(func): return "%s%s" % ( func.__name__, inspect.formatargspec(*inspect.getargspec(func)), )