add configurable traits to api docs

docs/sphinxext/autodoc_traits.py

@@ -0,0 +1,49 @@
+"""autodoc extension for configurable traits"""
+
+from traitlets import TraitType
+from sphinx.domains.python import PyClassmember
+from sphinx.ext.autodoc import ClassDocumenter, AttributeDocumenter
+
+
+class ConfigurableDocumenter(ClassDocumenter):
+    """Specialized Documenter subclass for traits with config=True"""
+    objtype = 'configurable'
+    directivetype = 'class'
+
+    def get_object_members(self, want_all):
+        """Add traits with .tag(config=True) to members list"""
+        check, members = super().get_object_members(want_all)
+        get_traits = self.object.class_own_traits if self.options.inherited_members \
+                     else self.object.class_traits
+        trait_members = []
+        for name, trait in sorted(get_traits(config=True).items()):
+            # put help in __doc__ where autodoc will look for it
+            trait.__doc__ = trait.help
+            trait_members.append((name, trait))
+        return check, trait_members + members
+
+
+class TraitDocumenter(AttributeDocumenter):
+    objtype = 'trait'
+    directivetype = 'attribute'
+    member_order = 1
+    priority = 100
+
+    @classmethod
+    def can_document_member(cls, member, membername, isattr, parent):
+        return isinstance(member, TraitType)
+
+    def format_name(self):
+        return 'config c.' + super().format_name()
+
+    def add_directive_header(self, sig):
+        sig = ' = {}(default={!r})'.format(
+            self.object.__class__.__name__,
+            self.object.default(),
+        )
+        return super().add_directive_header(sig)
+
+
+def setup(app):
+    app.add_autodocumenter(ConfigurableDocumenter)
+    app.add_autodocumenter(TraitDocumenter)