upstream/ipython Files · IPython/utils/nested_context.py

inputhook: disable CTRL+C when a hook is active....

inputhook: disable CTRL+C when a hook is active. On systems with 'readline', it's very likely to intercept a signal during a select() call. The default SIGINT handler will schedule a KeyboardInterrupt exception to be raised as soon as possible. If ctypes is used to install a Python callback for PyOS_InputHook, this will happen as soon as the bytecode execution starts, so even if the first instruction of the callback is a `try: ... except KeyboardInterrupt` clause, it's actually too late. As ctypes doesn't allow a Python callback to raise an exception, this ends up with IPython detecting an internal error... not pretty. We must therefore ignore the SIGINT signals until we are sure the exception handler is active, in the Python callback.

Thomas Kluyver - - Load All Authors

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             nested_context.py
        
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      """Backwards compatibility - we use contextlib.nested to support Python 2.6,

      but it's removed in Python 3.2."""

      # TODO : Remove this once we drop support for Python 2.6, and use

      # "with a, b:" instead.

      import sys

      from contextlib import contextmanager

      @contextmanager

      def nested(*managers):

          """Combine multiple context managers into a single nested context manager.

         This function has been deprecated in favour of the multiple manager form

         of the with statement.

         The one advantage of this function over the multiple manager form of the

         with statement is that argument unpacking allows it to be

         used with a variable number of context managers as follows:

            with nested(*managers):

                do_something()

          """

          exits = []

          vars = []

          exc = (None, None, None)

          try:

              for mgr in managers:

                  exit = mgr.__exit__

                  enter = mgr.__enter__

                  vars.append(enter())

                  exits.append(exit)

              yield vars

          except:

              exc = sys.exc_info()

          finally:

              while exits:

                  exit = exits.pop()

                  try:

                      if exit(*exc):

                          exc = (None, None, None)

                  except:

                      exc = sys.exc_info()

              if exc != (None, None, None):

                  # Don't rely on sys.exc_info() still containing

                  # the right information. Another exception may

                  # have been raised and caught by an exit method

                  raise exc[0], exc[1], exc[2]

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				"""Backwards compatibility - we use contextlib.nested to support Python 2.6,
				but it's removed in Python 3.2."""

				# TODO : Remove this once we drop support for Python 2.6, and use
				# "with a, b:" instead.

				import sys

				from contextlib import contextmanager

				@contextmanager
				def nested(*managers):
				"""Combine multiple context managers into a single nested context manager.

				This function has been deprecated in favour of the multiple manager form
				of the with statement.

				The one advantage of this function over the multiple manager form of the
				with statement is that argument unpacking allows it to be
				used with a variable number of context managers as follows:

				with nested(*managers):
				do_something()

				"""
				exits = []
				vars = []
				exc = (None, None, None)
				try:
				for mgr in managers:
				exit = mgr.__exit__
				enter = mgr.__enter__
				vars.append(enter())
				exits.append(exit)
				yield vars
				except:
				exc = sys.exc_info()
				finally:
				while exits:
				exit = exits.pop()
				try:
				if exit(*exc):
				exc = (None, None, None)
				except:
				exc = sys.exc_info()
				if exc != (None, None, None):
				# Don't rely on sys.exc_info() still containing
				# the right information. Another exception may
				# have been raised and caught by an exit method
				raise exc[0], exc[1], exc[2]