The cross module inheritance example is now working. Aside from my figuring out waf, there

are two key things that were necessary:

1.  We have to turn off the -fvisibility=hidden flag, since this hides the symbols in our
    shared libraries from others.  There's probably a better way to handle this, but this
    is expedient for now.

2.  Since I'm testing with GNU compilers & linkers, I have to use the magic lines in python
    before importing the inter-dependent modules (see test_cross_module_inheritance.py):

    import sys, ctypes
    sys.setdlopenflags(sys.getdlopenflags() | ctypes.RTLD_GLOBAL)

    This shouldn't be necessary on all platforms.

examples/cross_module_inheritance/test_cross_module_inheritance.py

@@ -0,0 +1,9 @@
+# This bit of magic is required for GNU compilers for now for resolving symbols
+# across libraries.  See many rants online regarding this issue...
+import sys, ctypes
+sys.setdlopenflags(sys.getdlopenflags() | ctypes.RTLD_GLOBAL)
+
+import A, B
+
+b = B.Derived()
+print isinstance(b, A.Base)

examples/cross_module_inheritance/wscript

@@ -2,33 +2,26 @@
 
 def build(bld):
 
-    for src, tgt in (('Agen.py', 'Amodule.cc'),
-                     ('Bgen.py', 'Bmodule.cc')):
-        gen = bld.new_task_gen(
-            features='command',
-            source=src,
-            target=tgt,
-            command='${PYTHON} ${SRC[0]} ${TGT[0]}')
+    for src, tgt in (("Agen.py", "Amodule.cc"),
+                     ("Bgen.py", "Bmodule.cc")):
+        gen = bld.new_task_gen(features="command",
+                               source=src,
+                               target=tgt,
+                               command="${PYTHON} ${SRC[0]} ${TGT[0]}")
 
-    if bld.env['CXX']:
-        # bld.shlib(source = 'Amodule.cc',
-        #           target = 'A',
-        #           features = 'pyext',
-        #           use = ['PYTHON'])
-        # bld.shlib(source = 'Bmodule.cc',
-        #           target = 'B',
-        #           features = 'pyext',
-        #           use = ['PYTHON', 'A'])
+    if bld.env["CXX"]:
+        obj = bld.new_task_gen(features="cxx cxxshlib pyext",
+                               source = "Amodule.cc",
+                               target = "A",
+                               install_path = None,                # do not install
+                               includes = ".",
+                               cxxflags = "-fvisibility=default",  # Hack for gcc only -- need to clean up
+                               )
 
-        obj = bld.new_task_gen(features=['cxx', 'cxxshlib', 'pyext'])
-        obj.source = ['Amodule.cc']
-        obj.target = 'A'
-        obj.install_path = None # do not install
-        obj.includes = '.'
-
-        obj = bld.new_task_gen(features=['cxx', 'cxxshlib', 'pyext'])
-        obj.source = ['Bmodule.cc']
-        obj.target = 'B'
-        obj.install_path = None # do not install
-        obj.includes = '.'
-        obj.links = ['A']
+        obj = bld.new_task_gen(features="cxx cxxshlib pyext",
+                               source = "Bmodule.cc",
+                               target = "B",
+                               install_path = None,                # do not install
+                               includes = ".",
+                               cxxflags = "-fvisibility=default",  # Hack for gcc only -- need to clean up
+                               )

wscript

@@ -286,11 +286,14 @@ def configure(conf):
                 else:
                     conf.env['ENABLE_PYGCCXML'] = True
 
-        # -fvisibility=hidden optimization
-        if (conf.env['CXX_NAME'] == 'gcc' and [int(x) for x in conf.env['CC_VERSION']] >= [4,0,0]
-            and conf.check_compilation_flag('-fvisibility=hidden')):
-            conf.env.append_value('CXXFLAGS_PYEXT', '-fvisibility=hidden')
-            conf.env.append_value('CCFLAGS_PYEXT', '-fvisibility=hidden')
+        # This breaks the ability to use cross-module dependencies (such as shown in 
+        # examples/cross_module_inheritance), so I'm turning off the hidden flag for 
+        # now.  I welcome a better solution!
+        # # -fvisibility=hidden optimization
+        # if (conf.env['CXX_NAME'] == 'gcc' and [int(x) for x in conf.env['CC_VERSION']] >= [4,0,0]
+        #     and conf.check_compilation_flag('-fvisibility=hidden')):
+        #     conf.env.append_value('CXXFLAGS_PYEXT', '-fvisibility=hidden')
+        #     conf.env.append_value('CCFLAGS_PYEXT', '-fvisibility=hidden')
 
         # Add include path for our stdint.h replacement, if needed (pstdint.h)
         if not conf.check_nonfatal(header_name='stdint.h'):