Make provided/implementedBy and adapter registries respect super().issue11

The query functions now start by looking at the next class in the MRO (interfaces directly provided by the underlying object are not found).

Adapter registries automatically pick up providedBy change to start finding the correct implementations of adapters, but to make that really useful they needed to change to unpack super() arguments and pass __self__ to the factory.

Fixes #11

Unfortunately, this makes PyPy unable to build the C extensions.

Additional crash-safety for adapter lookup.

Make the C functions get the cache only after resolving the
``required`` into a tuple, in case of side-effects like...clearing the
cache. This could lead to the ``cache`` object being deallocated
before we used it.

Drop the ``tuplefy`` function in favor of a direct call to
``PySequence_Tuple``. It's what the ``tuple`` constructor would do
anyway and saves a few steps.

Make sure that getting ``providedBy(super())`` and
``implementedBy(super())`` have no side effects.

2 files changed, 28 insertions, 3 deletions

diff --git a/docs/adapter.rst b/docs/adapter.rst
index 6a728a3..50fcf8c 100644
--- a/docs/adapter.rst
+++ b/docs/adapter.rst
@@ -202,11 +202,11 @@ factories:
    ...     pass
 
    >>> @zope.interface.implementer(IR)
-   ... class X:
+   ... class X(object):
    ...     pass
 
    >>> @zope.interface.implementer(IProvide1)
-   ... class Y:
+   ... class Y(object):
    ...     def __init__(self, context):
    ...         self.context = context
 
@@ -238,6 +238,29 @@ We can register and lookup by name too:
   >>> y.context is x
   True
 
+Passing ``super`` objects works as expected to find less specific adapters:
+
+.. doctest::
+
+  >>> class IDerived(IR):
+  ...     pass
+  >>> @zope.interface.implementer(IDerived)
+  ... class Derived(X):
+  ...     pass
+  >>> class DerivedAdapter(Y):
+  ...     def query_next(self):
+  ...        return registry.queryAdapter(
+  ...            super(type(self.context), self.context),
+  ...            IProvide1)
+  >>> registry.register([IDerived], IProvide1, '', DerivedAdapter)
+  >>> derived = Derived()
+  >>> adapter = registry.queryAdapter(derived, IProvide1)
+  >>> adapter.__class__.__name__
+  'DerivedAdapter'
+  >>> adapter = adapter.query_next()
+  >>> adapter.__class__.__name__
+  'Y'
+
 When the adapter factory produces ``None``, then this is treated as if no
 adapter has been found. This allows us to prevent adaptation (when desired)
 and let the adapter factory determine whether adaptation is possible based on
diff --git a/docs/conf.py b/docs/conf.py
index 8a0f86a..464f652 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -17,7 +17,9 @@ import os
 import pkg_resources
 sys.path.append(os.path.abspath('../src'))
 rqmt = pkg_resources.require('zope.interface')[0]
-
+# Import and document the pure-python versions of things; they tend to have better
+# docstrings and signatures.
+os.environ['PURE_PYTHON'] = '1'
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.