Mar 9, 2020 · Jan 14, 2020
diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
    """

    # We maintain two mappings:
    #   callbacks: signal -> {cid -> callback}
    #   _func_cid_map: signal -> {callback -> cid}
    # (actually, callbacks are weakrefs to the actual callbacks).
    #   callbacks: signal -> {cid -> weakref-to-callback}
    #   _func_cid_map: signal -> {weakref-to-callback -> cid}

    def __init__(self, exception_handler=_exception_printer):
        self.exception_handler = exception_handler
        self.callbacks = {}
        self._cid_gen = itertools.count()
        self._func_cid_map = {}

    # In general, callbacks may not be pickled; thus, we simply recreate an
    # empty dictionary at unpickling.  In order to ensure that `__setstate__`
    # (which just defers to `__init__`) is called, `__getstate__` must
    # return a truthy value (for pickle protocol>=3, i.e. Py3, the
    # *actual* behavior is that `__setstate__` will be called as long as
    # `__getstate__` does not return `None`, but this is undocumented -- see
    # http://bugs.python.org/issue12290).

    def __getstate__(self):
        return {'exception_handler': self.exception_handler}

    def __setstate__(self, state):
        self.__init__(**state)
        # In general, callbacks may not be pickled, so we just drop them.
        return {**vars(self), "callbacks": {}, "_func_cid_map": {}}

    def connect(self, s, func):
        """Register *func* to be called when signal *s* is generated.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -151,29 +151,18 @@ def h(exc):
		"""

		# We maintain two mappings:
		# callbacks: signal -> {cid -> callback}
		# _func_cid_map: signal -> {callback -> cid}
		# (actually, callbacks are weakrefs to the actual callbacks).
		# callbacks: signal -> {cid -> weakref-to-callback}
		# _func_cid_map: signal -> {weakref-to-callback -> cid}

		def __init__(self, exception_handler=_exception_printer):
		self.exception_handler = exception_handler
		self.callbacks = {}
		self._cid_gen = itertools.count()
		self._func_cid_map = {}

		# In general, callbacks may not be pickled; thus, we simply recreate an
		# empty dictionary at unpickling. In order to ensure that `__setstate__`
		# (which just defers to `__init__`) is called, `__getstate__` must
		# return a truthy value (for pickle protocol>=3, i.e. Py3, the
		# actual behavior is that `__setstate__` will be called as long as
		# `__getstate__` does not return `None`, but this is undocumented -- see
		# http://bugs.python.org/issue12290).

		def __getstate__(self):
		return {'exception_handler': self.exception_handler}

		def __setstate__(self, state):
		self.__init__(**state)
		# In general, callbacks may not be pickled, so we just drop them.
		return {**vars(self), "callbacks": {}, "_func_cid_map": {}}

		def connect(self, s, func):
		"""Register func to be called when signal s is generated.
Expand Down