Use metaclass for constructing RemoteInterface

MANIFEST.in

@@ -7,3 +7,4 @@ include tox.ini .coveragerc
 include misc/classify_foolscap.py
 include versioneer.py
 include src/foolscap/_version.py
+include src/foolscap/py.typed

setup.py

@@ -76,6 +76,10 @@ def run(self):
         },
 }
 
+setup_args.update(
+    include_package_data=True,
+)
+
 if __name__ == "__main__":
     setup(**setup_args)
 

src/foolscap/remoteinterface.py

@@ -1,4 +1,5 @@
 
+import six
 import types
 import inspect
 from zope.interface import interface, providedBy, implementer
@@ -28,10 +29,9 @@ class RemoteInterfaceClass(interface.InterfaceClass):
 
     """
 
-    def __init__(self, iname, bases=(), attrs=None, __module__=None):
+    def __init__(self, iname, bases=(), attrs=None):
         if attrs is None:
-            interface.InterfaceClass.__init__(self, iname, bases, attrs,
-                                              __module__)
+            interface.InterfaceClass.__init__(self, iname, bases, attrs)
             return
 
         # parse (and remove) the attributes that make this a RemoteInterface
@@ -41,8 +41,7 @@ def __init__(self, iname, bases=(), attrs=None, __module__=None):
             raise
 
         # now let the normal InterfaceClass do its thing
-        interface.InterfaceClass.__init__(self, iname, bases, attrs,
-                                          __module__)
+        interface.InterfaceClass.__init__(self, iname, bases, attrs)
 
         # now add all the remote methods that InterfaceClass would have
         # complained about. This is really gross, and it really makes me
@@ -92,10 +91,6 @@ def _parseRemoteInterface(self, iname, attrs):
 
         return remote_name, remote_attrs
 
-RemoteInterface = RemoteInterfaceClass("RemoteInterface",
-                                       __module__="pb.flavors")
-
-
 
 def getRemoteInterface(obj):
     """Get the (one) RemoteInterface supported by the object, or None."""
@@ -412,3 +407,10 @@ def _makeConstraint(t):
     return LocalInterfaceConstraint(t)
 
 addToConstraintTypeMap(interface.InterfaceClass, _makeConstraint)
+
+
+# See
+# https://github.com/warner/foolscap/pull/76/commits/ff3b9e8c1e4fa13701273a2143ba80b1e58f47cf#r549428977
+# for more background on the use of add_metaclass here.
+class RemoteInterface(six.with_metaclass(RemoteInterfaceClass, interface.Interface)):
+    pass