rework context docs

flask/ctx.py

@@ -24,18 +24,60 @@ _sentinel = object()
 
 
 class _AppCtxGlobals(object):
-    """A plain object."""
+    """A plain object. Used as a namespace for storing data during an
+    application context.
+
+    Creating an app context automatically creates this object, which is
+    made available as the :data:`g` proxy.
+
+    .. describe:: 'key' in g
+
+        Check whether an attribute is present.
+
+        .. versionadded:: 0.10
+
+    .. describe:: iter(g)
+
+        Return an iterator over the attribute names.
+
+        .. versionadded:: 0.10
+    """
 
     def get(self, name, default=None):
+        """Get an attribute by name, or a default value. Like
+        :meth:`dict.get`.
+
+        :param name: Name of attribute to get.
+        :param default: Value to return if the attribute is not present.
+
+        .. versionadded:: 0.10
+        """
         return self.__dict__.get(name, default)
 
     def pop(self, name, default=_sentinel):
+        """Get and remove an attribute by name. Like :meth:`dict.pop`.
+
+        :param name: Name of attribute to pop.
+        :param default: Value to return if the attribute is not present,
+            instead of raise a ``KeyError``.
+
+        .. versionadded:: 0.11
+        """
         if default is _sentinel:
             return self.__dict__.pop(name)
         else:
             return self.__dict__.pop(name, default)
 
     def setdefault(self, name, default=None):
+        """Get the value of an attribute if it is present, otherwise
+        set and return a default value. Like :meth:`dict.setdefault`.
+
+        :param name: Name of attribute to get.
+        :param: default: Value to set and return if the attribute is not
+            present.
+
+        .. versionadded:: 0.11
+        """
         return self.__dict__.setdefault(name, default)
 
     def __contains__(self, item):