Always depend on zope.hookable

And remove our Python implementation that was added in 2009. The two
have now diverged with new features in zope.hookable.

Since 2012, zope.hookable has had a Python implementation. Now, with
4.2, the C extension is an optional build.

.coveragerc

@@ -1,8 +1,10 @@
 [run]
 source = zope.component
 omit =
-    src/zope/component/standalonetests.py
     # Runs in a subprocess
+    src/zope/component/standalonetests.py
+    # Not used
+    src/zope/component/hookable.py
 
 [report]
 exclude_lines =

CHANGES.rst

@@ -4,7 +4,9 @@ Changes
 4.4.2 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- Always install ``zope.hookable`` as a dependency (the ``hook``
+  extra is now empty). ``zope.hookable`` respects the PURE_PYTHON
+  environment variable, and has an optional C extension.
 
 
 4.4.1 (2017-09-26)

setup.py

@@ -23,7 +23,6 @@
 from setuptools import setup, find_packages
 
 HOOK_REQUIRES = [
-    'zope.hookable',
 ]
 
 PERSISTENTREGISTRY_REQUIRES = [
@@ -99,13 +98,14 @@ def read(*rnames):
     tests_require=TESTS_REQUIRE,
     install_requires=[
         'setuptools',
-        'zope.interface>=4.1.0',
+        'zope.interface >= 4.1.0',
         'zope.event',
+        'zope.hookable >= 4.2.0',
     ],
     include_package_data=True,
     zip_safe=False,
     extras_require={
-        'hook': HOOK_REQUIRES,
+        'hook': HOOK_REQUIRES, # BWC
         'persistentregistry': PERSISTENTREGISTRY_REQUIRES,
         'security': SECURITY_REQUIRES,
         'zcml': ZCML_REQUIRES,

src/zope/component/_api.py

@@ -16,6 +16,8 @@
 import sys
 import types
 
+from zope.hookable import hookable
+
 from zope.interface import Interface
 from zope.interface import implementedBy
 from zope.interface import providedBy
@@ -30,12 +32,7 @@
 from zope.component._declaration import adapter
 from zope.component._declaration import adapts
 
-# Use the C implementation in zope.hookable, if available;  fall back
-# to our Python version if not.
-try:
-    from zope.hookable import hookable
-except ImportError: #pragma NO COVER
-    from zope.component.hookable import hookable
+
 
 # getSiteManager() returns a component registry.  Although the term
 # "site manager" is deprecated in favor of "component registry",

src/zope/component/hookable.py

@@ -11,23 +11,8 @@
 # FOR A PARTICULAR PURPOSE.
 #
 ##############################################################################
-""" This module supplies a pure-Python version of zope.hookable.hookable.
 """
-class hookable(object):
-    __slots__ = ('__original', '__implementation')
-
-    original = property(lambda self: self.__original,)
-    implementation = property(lambda self: self.__implementation,)
-
-    def __init__(self, implementation):
-        self.__original = self.__implementation = implementation
-
-    def sethook(self, newimplementation):
-        old, self.__implementation = self.__implementation, newimplementation
-        return old
-
-    def reset(self):
-        self.__implementation = self.__original
-
-    def __call__(self, *args, **kw):
-        return self.__implementation(*args, **kw)
+This module is deprecated. Prefer to use zope.hookable.hookable.
+"""
+from zope.hookable import hookable
+hookable = hookable # BWC

src/zope/component/tests/test_security.py

@@ -11,7 +11,8 @@
 # FOR A PARTICULAR PURPOSE.
 #
 ##############################################################################
-"""Pure-Python hookable tests
+"""
+Tests for zope.component.security
 """
 import unittest