Patch #1520294: Support for getset and member descriptors in types.py,

inspect.py, and pydoc.py.  Specifically, this allows for querying the type of
an object against these built-in C types and more importantly, for getting
their docstrings printed in the interactive interpreter's help() function.

This patch includes a new built-in module called _types which provides
definitions of getset and member descriptors for use by the types.py module.
These types are exposed as types.GetSetDescriptorType and
types.MemberDescriptorType.  Query functions are provided as
inspect.isgetsetdescriptor() and inspect.ismemberdescriptor().  The
implementations of these are robust enough to work with Python implementations
other than CPython, which may not have these fundamental types.

The patch also includes documentation and test suite updates.

I commit these changes now under these guiding principles:

1. Silence is assent.  The release manager has not said "no", and of the few
   people that cared enough to respond to the thread, the worst vote was "0".

2. It's easier to ask for forgiveness than permission.

3. It's so dang easy to revert stuff in svn, that you could view this as a
   forcing function. :)

Windows build patches will follow.

1 files changed, 21 insertions, 1 deletions

diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index ff6e7ca..0fc624e 100755
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -318,6 +318,8 @@ class Doc:
         # identifies something in a way that pydoc itself has issues handling;
         # think 'super' and how it is a descriptor (which raises the exception
         # by lacking a __name__ attribute) and an instance.
+        if inspect.isgetsetdescriptor(object): return self.docdata(*args)
+        if inspect.ismemberdescriptor(object): return self.docdata(*args)
         try:
             if inspect.ismodule(object): return self.docmodule(*args)
             if inspect.isclass(object): return self.docclass(*args)
@@ -333,7 +335,7 @@ class Doc:
             name and ' ' + repr(name), type(object).__name__)
         raise TypeError, message
 
-    docmodule = docclass = docroutine = docother = fail
+    docmodule = docclass = docroutine = docother = docproperty = docdata = fail
 
     def getdocloc(self, object):
         """Return the location of module docs or None"""
@@ -915,6 +917,10 @@ class HTMLDoc(Doc):
         lhs = name and '<strong>%s</strong> = ' % name or ''
         return lhs + self.repr(object)
 
+    def docdata(self, object, name=None, mod=None, cl=None):
+        """Produce html documentation for a data descriptor."""
+        return self._docdescriptor(name, object, mod)
+
     def index(self, dir, shadowed=None):
         """Generate an HTML index for a directory of modules."""
         modpkgs = []
@@ -1268,6 +1274,10 @@ class TextDoc(Doc):
         """Produce text documentation for a property."""
         return self._docdescriptor(name, object, mod)
 
+    def docdata(self, object, name=None, mod=None, cl=None):
+        """Produce text documentation for a data descriptor."""
+        return self._docdescriptor(name, object, mod)
+
     def docother(self, object, name=None, mod=None, parent=None, maxlen=None, doc=None):
         """Produce text documentation for a data object."""
         repr = self.repr(object)
@@ -1397,6 +1407,14 @@ def describe(thing):
             return 'module ' + thing.__name__
     if inspect.isbuiltin(thing):
         return 'built-in function ' + thing.__name__
+    if inspect.isgetsetdescriptor(thing):
+        return 'getset descriptor %s.%s.%s' % (
+            thing.__objclass__.__module__, thing.__objclass__.__name__,
+            thing.__name__)
+    if inspect.ismemberdescriptor(thing):
+        return 'member descriptor %s.%s.%s' % (
+            thing.__objclass__.__module__, thing.__objclass__.__name__,
+            thing.__name__)
     if inspect.isclass(thing):
         return 'class ' + thing.__name__
     if inspect.isfunction(thing):
@@ -1453,6 +1471,8 @@ def doc(thing, title='Python Library Documentation: %s', forceload=0):
         if not (inspect.ismodule(object) or
                 inspect.isclass(object) or
                 inspect.isroutine(object) or
+                inspect.isgetsetdescriptor(object) or
+                inspect.ismemberdescriptor(object) or
                 isinstance(object, property)):
             # If the passed object is a piece of data or an instance,
             # document its available methods instead of its value.