.

component/ZEO/buildout.cfg

@@ -31,6 +31,8 @@ init =
 
     # update [versions] from what is needed by ZEO<X>
     for _ in zeo_x['egg_versions'].splitlines():
+      if _.startswith('#'):
+          continue
       egg, eq, version = _.split() # 'transaction = 1.7.0'
       assert eq == '='
       self.buildout['versions'][egg] = version

component/ZODB/buildout.cfg

@@ -22,14 +22,24 @@ major  = 4
 init =
   # link/depend ZODB -> ZODB<X>
   zodb_x = 'ZODB'+options['major']
-  options['depends'] = '$${%s:egg}' % zodb_x
   zodb_x = self.buildout[zodb_x]
+  options['depends'] = '$${%s:egg}' % zodb_x.name
+
   options['egg'] = zodb_x['egg']
   options['location'] = zodb_x['setup']
 
+  # for ZODB3 also depend on _ZODB3-{ZODB,persistent,BTrees,ZEO}.
+  # installing those eggs ensures forward compatibiluty with ZODB4/5 where
+  # instead of single ZODB3 egg, there are separate ZDOB,persistent,BTrees,... distributions.
+  if options['major'] == '3':
+    for egg in ['ZODB','persistent','BTrees','ZEO']:
+      z3egg = self.buildout['_ZODB3-%s' % egg]
+      options['depends'] += '\n$${%s:egg}' % z3egg.name
+
   # update [versions] from what is needed by ZODB<X>
-  # XXX do not change egg version if it is already speficified in [versions] ?
   for _ in zodb_x['egg_versions'].splitlines():
+    if _.startswith('#'):
+        continue
     egg, eq, version = _.split() # 'transaction = 1.7.0'
     assert eq == '='
     self.buildout['versions'][egg] = version
@@ -52,18 +62,32 @@ repository = https://lab.nexedi.com/kirr/ZODB.git
 #location = ${buildout:parts-directory}/ZODB	# XXX
 git-executable = ${git:location}/bin/git
 
-# ZODB4: we maintain our own 4-nxd branch with patches for wendelin.core to work
-# correctly. The patches are backports of what is in ZODB master (ZODB5).
-[ZODB4]
+[_ZODB45]
 recipe  = zc.recipe.egg:develop
-setup   = ${ZODB4-repository:location}
 egg     = ZODB
 depends = ${persistent:egg} ${BTrees:egg}
 
+# eggs versions that are used by all ZODB{4,5}.
 egg_versions =
-  transaction = 1.7.0
+  # TODO update to 4.7.3 once it is released
+  Btrees = 4.5.1
+  persistent = 4.6.4
+  # TODO update to 2.0.0 once NEO stops doing bytes._pack = ...
+  # https://lab.nexedi.com/nexedi/slapos/commit/27f574bc
+  zodbpickle = 1.0.4
+
+  # XXX explain about ZODB3
   ZODB3 = 3.11.0
-# XXX explain about ZODB3
+
+
+# ZODB4: we maintain our own 4-nxd branch with patches for wendelin.core to work
+# correctly. The patches are backports of what is in ZODB master (ZODB5).
+[ZODB4]
+<= _ZODB45
+setup = ${ZODB4-repository:location}
+
+egg_versions +=
+  transaction = 1.7.0
 
 [ZODB4-repository]
 <= _ZODB-git-repository
@@ -90,18 +114,36 @@ location = ${buildout:parts-directory}/ZODB3
 branch  = 3.10-nxd--t
 #revision= ...	XXX pin
 
+# Stub eggs for ZODB3 to be forward-compatible with ZODB4/5.
+[_ZODB3-ZODB45-compat-egg]
+recipe  = zc.recipe.egg:develop
+setup   = ${ZODB3-repository:location}/ZODB45-compat/${:egg}/setup.py
+depends = ${ZODB3:recipe}
+
+[_ZODB3-ZODB]
+<= _ZODB3-ZODB45-compat-egg
+egg = ZODB
+
+[_ZODB3-persistent]
+<= _ZODB3-ZODB45-compat-egg
+egg = persistent
+
+[_ZODB3-BTrees]
+<= _ZODB3-ZODB45-compat-egg
+egg = BTrees
+
+[_ZODB3-ZEO]
+<= _ZODB3-ZODB45-compat-egg
+egg = ZEO
+
 
 # ZODB5: pristine upstream
 [ZODB5]
-recipe  = zc.recipe.egg:develop
-setup   = ${ZODB5-repository:location}
-egg     = ZODB
-depends = ${persistent:egg} ${BTrees:egg}
+<= _ZODB45
+setup = ${ZODB5-repository:location}
 
 egg_versions =
   transaction = 2.4.0
-  ZODB3 = 3.11.0
-# XXX explain about ZODB3
 
 [ZODB5-repository]
 <= _ZODB-git-repository
@@ -109,6 +151,7 @@ location = ${buildout:parts-directory}/ZODB5
 branch  = master
 #revision= ...	XXX pin
 
+
 # XXX: buildout fails to install properly eggs with setup_requires
 [BTrees]
 recipe = zc.recipe.egg:custom
@@ -120,13 +163,3 @@ recipe = zc.recipe.egg:custom
 egg = ${:_buildout_section_name_}
 setup-eggs = ${python-cffi:egg}
 ###
-
-
-# eggs versions that are used by all all ZODB<X>.
-[versions]
-# TODO update to 4.7.3 once it is released
-Btrees = 4.5.1
-persistent = 4.6.4
-# TODO update to 2.0.0 once NEO stops doing bytes._pack = ...
-# https://lab.nexedi.com/nexedi/slapos/commit/27f574bc
-zodbpickle = 1.0.4