X Stub ZODB/persistent/BTrees/ZEO have to be installed manually for...

X Stub ZODB/persistent/BTrees/ZEO have to be installed manually for forward-compatibility with ZODB4 and ZODB5

Else installing any egg that depends on 'ZODB' (not 'ZODB3') will pull
in ZODB5. Example of those eggs are zodbtools, zodburi, ...

ZODB45-compat/BTrees/setup.py

+../ZODB/setup.py
\ No newline at end of file

ZODB45-compat/ZEO/setup.py

+../ZODB/setup.py
\ No newline at end of file

ZODB45-compat/ZODB/setup.py

+# XXX doc
+
+from setuptools import setup
+from os.path import basename, dirname, join
+import re
+
+# find our name (ZODB/BTrees/persistent/ZEO)
+NAME = basename(dirname(__file__))  # .../ZODB45-compat/ZODB/setup.py -> ZODB
+
+# find out ZODB3 version
+
+# grep searches text for pattern.
+# return re.Match object or raises if pattern was not found.
+def grep1(pattern, text):
+    rex = re.compile(pattern, re.MULTILINE)
+    m = rex.search(text)
+    if m is None:
+        raise RuntimeError('%r not found' % pattern)
+    return m
+
+# read file content
+def readfile(path):
+    with open(path, 'r') as f:
+        return f.read()
+
+_ = readfile(join(dirname(__file__), '../../setup.py'))
+_ = grep1('^VERSION = "(.*)"$', _)
+VERSION = _.group(1)
+
+
+# setup stub ZODB/BTrees/... egg that just depends on ZODB3
+setup(name=NAME,
+      version=VERSION,
+      packages = [],
+      install_requires = ['ZODB3 == %s' % VERSION],
+)

ZODB45-compat/persistent/setup.py

+../ZODB/setup.py
\ No newline at end of file

setup.py

@@ -182,6 +182,12 @@ long_description = str(
     )+ '''\n\n.. |Lowis| unicode:: L \\xf6 wis\n'''
 
 setup(name="ZODB3",
+      # XXX there is also provides-dist
+      #     -> https://packaging.python.org/specifications/core-metadata/#rarely-used-fields
+      #        https://www.python.org/dev/peps/pep-0314/#provides-multiple-use
+      #        https://www.python.org/dev/peps/pep-0345/#provides-dist-multiple
+      #
+      # https://github.com/pypa/packaging-problems/issues/154   (obsoletes/provides not supported)
       provides=["ZODB", "persistent", "BTrees", "ZEO"], # XXX doc
       version=VERSION,
       maintainer="Zope Foundation and Contributors",