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

Python vs IPython: recommend %cd, %env over !cd, !export...

Python vs IPython: recommend %cd, %env over !cd, !export The quick overview mentioned `!cd DIR` among examples of shell commands one might use —but that doesn't work as user would hope (can only affect commands in same ! e.g. `!cd /; pwd`). That's not as bad now that `!cd` prints a warning, but IMHO better to provide the right mental model up front. => Replaced that with minimal motivation why `!cd` and `!export` can't work, recommending some %magic alternatives; moved it out of examples to not distract, and right before Magics section.

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             refbug.py
        
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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.

      """

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

      # Module imports

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

      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 "_refbug_cache" not 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.
				"""

				#-----------------------------------------------------------------------------
				# Module imports
				#-----------------------------------------------------------------------------

				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 "_refbug_cache" not 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())