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

Refuse to install event loop hooks when not using `prompt_toolkit` (#14132)...

Refuse to install event loop hooks when not using `prompt_toolkit` (#14132) Without this, `%gui` is effectively a no-op but the user thinks it works. For example. If running `ipython`: ``` In [1]: import matplotlib; matplotlib.use('QtAgg'); from matplotlib import pyplot; pyplot.ion(); pyplot.plot([1, 2, 3, 4]) Installed qt6 event loop hook. Out[1]: [<matplotlib.lines.Line2D at 0x1ba2f59d2a0>] ``` The window appears and responds as expected. If running `ipython --simple-prompt`, the user would see the same output, when in fact no event loop hook was installed since it's not supported without `prompt_toolkit`. The resulting Qt window is unresponsive because the event loop is not running, i.e. with `--simple-prompt`, Qt windows should block (but `pyplot` doesn't/can't know to do that) With this PR, the user will see: ``` In [1]: import matplotlib; matplotlib.use('QtAgg'); from matplotlib import pyplot; pyplot.ion(); pyplot.plot([1, 2, 3, 4]) Cannot install event loop hook for "qt" when running with `--simple-prompt`. NOTE: Tk is supported natively; use Tk apps and Tk backends with `--simple-prompt`. Out[1]: [<matplotlib.lines.Line2D at 0x170be0c0310>] ``` They'll still get an unresponsive Qt window, but they'll at least be told this can't work (while anything using Tk will work just fine).

Paul Ivanov - - Load All Authors

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      """Simple script to be run *twice*, to check reference counting bugs.

      See test_run for details."""

      import sys

      # We want to ensure that while objects remain available for immediate access,

      # objects from *previous* runs of the same script get collected, to avoid

      # accumulating massive amounts of old references.

      class C(object):

          def __init__(self,name):

              self.name = name

              self.p = print

              self.flush_stdout = sys.stdout.flush

          def __del__(self):

              self.p('tclass.py: deleting object:',self.name)

              self.flush_stdout()

      try:

          name = sys.argv[1]

      except IndexError:

          pass

      else:

          if name.startswith('C'):

              c = C(name)

      #print >> sys.stderr, "ARGV:", sys.argv  # dbg

      # This next print statement is NOT debugging, we're making the check on a

      # completely separate process so we verify by capturing stdout:

      print('ARGV 1-:', sys.argv[1:])

      sys.stdout.flush()

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				"""Simple script to be run twice, to check reference counting bugs.

				See test_run for details."""


				import sys

				# We want to ensure that while objects remain available for immediate access,
				# objects from previous runs of the same script get collected, to avoid
				# accumulating massive amounts of old references.
				class C(object):
				def __init__(self,name):
				self.name = name
				self.p = print
				self.flush_stdout = sys.stdout.flush

				def __del__(self):
				self.p('tclass.py: deleting object:',self.name)
				self.flush_stdout()

				try:
				name = sys.argv[1]
				except IndexError:
				pass
				else:
				if name.startswith('C'):
				c = C(name)

				#print >> sys.stderr, "ARGV:", sys.argv # dbg

				# This next print statement is NOT debugging, we're making the check on a
				# completely separate process so we verify by capturing stdout:
				print('ARGV 1-:', sys.argv[1:])
				sys.stdout.flush()