Merge pull request #1530 from gevent/issue1596

Remove the deprecated magic proxy gevent.signal.

CHANGES.rst

@@ -49,6 +49,15 @@ Library and Dependency Updates
   because of the limited amount of actual allocation that gets done
   this is not expected to be a bottleneck.
 
+Potentially Breaking Changes
+----------------------------
+
+- Remove the magic proxy object ``gevent.signal``. This served as both
+  a deprecated alias of `gevent.signal_handler` *and* the module
+  `gevent.signal`. This made it confusing to humans and static
+  analysis tools alike. The alias was deprecated since gevent 1.1b4.
+  See :issue:`1596`.
+
 Other
 -----
 
@@ -78,6 +87,7 @@ Other
   before the gevent resolver was initialized. Reported in
   :issue:`1526` by Chris Utz and Josh Zuech.
 
+
 1.5a3 (2020-01-01)
 ==================
 

docs/api/gevent.rst

@@ -103,34 +103,7 @@ Working with multiple processes
 Signals
 =======
 
-.. function:: signal_handler(signalnum, handler, *args, **kwargs)
-
-    Call the *handler* with the *args* and *kwargs* when the process
-    receives the signal *signalnum*.
-
-    The *handler* will be run in a new greenlet when the signal is delivered.
-
-    This returns an object with the useful method ``cancel``, which, when called,
-    will prevent future deliveries of *signalnum* from calling *handler*.
-
-    .. note::
-
-        This may not operate correctly with SIGCHLD if libev child watchers
-        are used (as they are by default with :func:`gevent.os.fork`).
-
-    .. versionchanged:: 1.1b4
-
-         ``gevent.signal`` is an alias for this function, included for
-         backwards compatibility; the new module :doc:`gevent.signal <gevent.signal>`
-         is replacing this name. This alias will be removed in a
-         future release.
-
-    .. versionchanged:: 1.2a1
-
-          The *handler* is required to be callable at construction time.
-
-.. This is also in the docstring of gevent.hub.signal, which is the
-   actual callable invoked
+.. autofunction:: signal_handler
 
 Timeouts
 ========

examples/portforwarder.py

@@ -97,8 +97,8 @@ def main():
     dest = parse_address(args[1])
     server = PortForwarder(source, dest)
     log('Starting port forwarder %s:%s -> %s:%s', *(server.address[:2] + dest))
-    gevent.signal(signal.SIGTERM, server.close)
-    gevent.signal(signal.SIGINT, server.close)
+    gevent.signal_handler(signal.SIGTERM, server.close)
+    gevent.signal_handler(signal.SIGINT, server.close)
     server.start()
     gevent.wait()
 

src/gevent/__init__.py

@@ -46,7 +46,6 @@ __all__ = [
     'killall',
     'reinit',
     'setswitchinterval',
-    'signal', # deprecated
     'signal_handler',
     'sleep',
     'spawn',
@@ -100,60 +99,11 @@ try:
 except ImportError:
     __all__.remove('fork')
 
-# See https://github.com/gevent/gevent/issues/648
-# A temporary backwards compatibility shim to enable users to continue
-# to treat 'from gevent import signal' as a callable, to matter whether
-# the 'gevent.signal' module has been imported first
-from gevent.hub import signal as _signal_class
-signal_handler = _signal_class
-from gevent import signal as _signal_module
-
-# The object 'gevent.signal' must:
-# - be callable, returning a gevent.hub.signal;
-# - answer True to isinstance(gevent.signal(...), gevent.signal);
-# - answer True to isinstance(gevent.signal(...), gevent.hub.signal)
-# - have all the attributes of the module 'gevent.signal';
-# - answer True to isinstance(gevent.signal, types.ModuleType) (optional)
-
-# The only way to do this is to use a metaclass, an instance of which (a class)
-# is put in sys.modules and is substituted for gevent.hub.signal.
-# This handles everything except the last one.
-
-
-class _signal_metaclass(type):
-
-    def __getattr__(cls, name):
-        return getattr(_signal_module, name)
-
-    def __setattr__(cls, name, value):
-        setattr(_signal_module, name, value)
-
-    def __instancecheck__(cls, instance):
-        return isinstance(instance, _signal_class)
-
-    def __dir__(cls):
-        return dir(_signal_module)
-
-
-class signal(object):
-
-    __doc__ = _signal_module.__doc__
-
-    def __new__(cls, *args, **kwargs):
-        return _signal_class(*args, **kwargs)
-
-
-# The metaclass is applied after the class declaration
-# for Python 2/3 compatibility
-signal = _signal_metaclass(str("signal"),
-                           (),
-                           dict(signal.__dict__))
-
-sys.modules['gevent.signal'] = signal
-sys.modules['gevent.hub'].signal = signal
-
-del sys
-
+# This used to be available as gevent.signal; that broke in 1.1b4 but
+# a temporary alias was added (See
+# https://github.com/gevent/gevent/issues/648). It was ugly and complex and
+# caused confusion, so it was removed in 1.5. See https://github.com/gevent/gevent/issues/1529
+from gevent.hub import signal as signal_handler
 
 # the following makes hidden imports visible to freezing tools like
 # py2exe. see https://github.com/gevent/gevent/issues/181

src/gevent/hub.py

@@ -213,25 +213,32 @@ def kill(greenlet, exception=GreenletExit):
 
 class signal(object):
     """
+    signal_handler(signalnum, handler, *args, **kwargs) -> object
+
     Call the *handler* with the *args* and *kwargs* when the process
     receives the signal *signalnum*.
 
-    The *handler* will be run in a new greenlet when the signal is delivered.
+    The *handler* will be run in a new greenlet when the signal is
+    delivered.
 
-    This returns an object with the useful method ``cancel``, which, when called,
-    will prevent future deliveries of *signalnum* from calling *handler*.
+    This returns an object with the useful method ``cancel``, which,
+    when called, will prevent future deliveries of *signalnum* from
+    calling *handler*.
 
     .. note::
 
-        This may not operate correctly with SIGCHLD if libev child watchers
-        are used (as they are by default with os.fork).
+        This may not operate correctly with ``SIGCHLD`` if libev child
+        watchers are used (as they are by default with
+        `gevent.os.fork`). See :mod:`gevent.signal` for a more
+        general purpose solution.
 
     .. versionchanged:: 1.2a1
-       The ``handler`` argument is required to be callable at construction time.
-    """
 
-    # XXX: This is manually documented in gevent.rst while it is aliased in
-    # the gevent module.
+        The ``handler`` argument is required to
+        be callable at construction time.
+    """
+    # This is documented as a function, not a class,
+    # so we're free to change implementation details.
 
     greenlet_class = None
 

src/gevent/signal.py

@@ -2,9 +2,9 @@
 Cooperative implementation of special cases of :func:`signal.signal`.
 
 This module is designed to work with libev's child watchers, as used
-by default in :func:`gevent.os.fork` Note that each ``SIGCHLD`` handler
-will be run in a new greenlet when the signal is delivered (just like
-:class:`gevent.hub.signal`)
+by default in :func:`gevent.os.fork` Note that each ``SIGCHLD``
+handler will be run in a new greenlet when the signal is delivered
+(just like :class:`gevent.hub.signal`)
 
 The implementations in this module are only monkey patched if
 :func:`gevent.os.waitpid` is being used (the default) and if
@@ -12,6 +12,11 @@ The implementations in this module are only monkey patched if
 information on configuring this not to be the case for advanced uses.
 
 .. versionadded:: 1.1b4
+.. versionchanged:: 1.5a4
+   Previously there was a backwards compatibility alias
+   ``gevent.signal``, introduced in 1.1b4, that partly shadowed this
+   module, confusing humans and static analysis tools alike. That alias
+   has been removed. (See `gevent.signal_handler`.)
 """
 
 from __future__ import absolute_import

src/gevent/tests/test__core_loop_run.py

 from __future__ import print_function
 import sys
-# Using a direct import of signal (deprecated).
-# We are also called from test__core_loop_run_sig_mod.py,
-# which has already done 'import gevent.signal' to be sure we work
-# when the module has been imported.
-from gevent import core, signal
+from gevent import core
+from gevent import signal_handler as signal
 loop = core.loop(default=False)
 
 

src/gevent/tests/test__core_loop_run_sig_mod.py

-import sys
-import gevent.signal
-assert gevent.signal # Get gevent.signal as a module, make sure our backwards compatibility kicks in
-
-import test__core_loop_run # this runs main tests, fails if signal() is not callable.
-assert test__core_loop_run # pyflakes
-
-from gevent.hub import signal as hub_signal
-from gevent import signal as top_signal # pylint:disable=reimported
-
-assert gevent.signal is hub_signal
-assert gevent.signal is top_signal
-assert hasattr(gevent.signal, 'signal')
-s = top_signal(2, sys.stderr.write, 'INTERRUPT')
-assert isinstance(s, top_signal)
-assert isinstance(s, hub_signal)

src/gevent/tests/test__hub_join_timeout.py

@@ -10,7 +10,7 @@ from gevent.testing.testcase import TimeAssertMixin
 SMALL_TICK = 0.05
 
 # setting up signal does not affect join()
-gevent.signal(1, lambda: None)  # wouldn't work on windows
+gevent.signal_handler(1, lambda: None)  # wouldn't work on windows
 
 
 def repeated(func, repetitions=2):

src/gevent/tests/test__signal.py

@@ -27,10 +27,11 @@ class TestSignal(greentest.TestCase):
     __timeout__ = greentest.LARGE_TIMEOUT
 
     def test_handler(self):
-        self.assertRaises(TypeError, gevent.signal, signal.SIGALRM, 1)
+        with self.assertRaises(TypeError):
+            gevent.signal_handler(signal.SIGALRM, 1)
 
     def test_alarm(self):
-        sig = gevent.signal(signal.SIGALRM, raise_Expected)
+        sig = gevent.signal_handler(signal.SIGALRM, raise_Expected)
         assert sig.ref is False, repr(sig.ref)
         sig.ref = True
         assert sig.ref is True