upstream/ipython Files · IPython/core/tests/refbug.py

Make event triggering robust to (un)registration....

Make event triggering robust to (un)registration. Event callbacks can register or unregister new callbacks for the same event while executing, and the previous triggering implementation allowed for event callbacks to be inadvertently skipped. The fix is to make a copy of the list of callbacks before executing any of them. With this change, the resulting semantics are simple: any callbacks registered before triggering are executed, and any new callbacks registered are only visible at the next triggering of the event. Note that this could potentially break existing callers who expected newly-appended callbacks were immediately executed. Fixes . Originally based on a patch by @marksandler2.

Thomas Kluyver - - Load All Authors

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      """Minimal script to reproduce our nasty reference counting bug.

      The problem is related to https://github.com/ipython/ipython/issues/141

      The original fix for that appeared to work, but John D. Hunter found a

      matplotlib example which, when run twice in a row, would break.  The problem

      were references held by open figures to internals of Tkinter.

      This code reproduces the problem that John saw, without matplotlib.

      This script is meant to be called by other parts of the test suite that call it

      via %run as if it were executed interactively by the user. As of 2011-05-29,

      test_run.py calls it.

      """

      from __future__ import print_function

      #-----------------------------------------------------------------------------

      # Module imports

      #-----------------------------------------------------------------------------

      import sys

      from IPython import get_ipython

      #-----------------------------------------------------------------------------

      # Globals

      #-----------------------------------------------------------------------------

      # This needs to be here because nose and other test runners will import

      # this module. Importing this module has potential side effects that we

      # want to prevent.

      if __name__ == '__main__':

          ip = get_ipython()

          if not '_refbug_cache' in ip.user_ns:

              ip.user_ns['_refbug_cache'] = []

          aglobal = 'Hello'

          def f():

              return aglobal

          cache = ip.user_ns['_refbug_cache']

          cache.append(f)

          def call_f():

              for func in cache:

                  print('lowercased:',func().lower())

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				"""Minimal script to reproduce our nasty reference counting bug.

				The problem is related to https://github.com/ipython/ipython/issues/141

				The original fix for that appeared to work, but John D. Hunter found a
				matplotlib example which, when run twice in a row, would break. The problem
				were references held by open figures to internals of Tkinter.

				This code reproduces the problem that John saw, without matplotlib.

				This script is meant to be called by other parts of the test suite that call it
				via %run as if it were executed interactively by the user. As of 2011-05-29,
				test_run.py calls it.
				"""
				from __future__ import print_function

				#-----------------------------------------------------------------------------
				# Module imports
				#-----------------------------------------------------------------------------
				import sys

				from IPython import get_ipython

				#-----------------------------------------------------------------------------
				# Globals
				#-----------------------------------------------------------------------------

				# This needs to be here because nose and other test runners will import
				# this module. Importing this module has potential side effects that we
				# want to prevent.
				if __name__ == '__main__':

				ip = get_ipython()

				if not '_refbug_cache' in ip.user_ns:
				ip.user_ns['_refbug_cache'] = []


				aglobal = 'Hello'
				def f():
				return aglobal

				cache = ip.user_ns['_refbug_cache']
				cache.append(f)

				def call_f():
				for func in cache:
				print('lowercased:',func().lower())