Use @DocInherit to put docstrings on render dispatch functions in base class.

decorators.py

@@ -0,0 +1,68 b''
+"""
+doc_inherit decorator
+
+Usage:
+
+class Foo(object):
+    def foo(self):
+        "Frobber"
+        pass
+
+class Bar(Foo):
+    @doc_inherit
+    def foo(self):
+        pass
+
+Now, Bar.foo.__doc__ == Bar().foo.__doc__ == Foo.foo.__doc__ == "Frobber"
+See: http://stackoverflow.com/questions/2025562/inherit-docstrings-in-python-class-inheritance
+"""
+
+from functools import wraps
+
+
+class DocInherit(object):
+    """
+    Docstring inheriting method descriptor
+
+    The class itself is also used as a decorator
+    """
+
+    def __init__(self, mthd):
+        self.mthd = mthd
+        self.name = mthd.__name__
+
+    def __get__(self, obj, cls):
+        if obj:
+            return self.get_with_inst(obj, cls)
+        else:
+            return self.get_no_inst(cls)
+
+    def get_with_inst(self, obj, cls):
+
+        overridden = getattr(super(cls, obj), self.name, None)
+
+        @wraps(self.mthd, assigned=('__name__', '__module__'))
+        def f(*args, **kwargs):
+            return self.mthd(obj, *args, **kwargs)
+
+        return self.use_parent_doc(f, overridden)
+
+    def get_no_inst(self, cls):
+
+        for parent in cls.__mro__[1:]:
+            overridden = getattr(parent, self.name, None)
+            if overridden: break
+
+        @wraps(self.mthd, assigned=('__name__', '__module__'))
+        def f(*args, **kwargs):
+            return self.mthd(*args, **kwargs)
+
+        return self.use_parent_doc(f, overridden)
+
+    def use_parent_doc(self, func, source):
+        if source is None:
+            raise NameError, ("Can't find '%s' in parents" % self.name)
+        func.__doc__ = source.__doc__
+        return func
+
+doc_inherit = DocInherit

nbconvert.py

@@ -16,7 +16,7 b' import sys'
 from IPython.external import argparse
 from IPython.nbformat import current as nbformat
 from IPython.utils.text import indent
-
+from decorators import DocInherit
 
 # Cell converters
 
@@ -88,21 +88,46 b' class Converter(object):'
         return infile
 
     def render_heading(self, cell):
+        """convert a heading cell
+
+        Returns list."""
         raise NotImplementedError
 
     def render_code(self, cell):
+        """Convert a code cell
+
+        Returns list."""
         raise NotImplementedError
 
     def render_markdown(self, cell):
+        """convert a markdown cell
+
+        Returns list."""
         raise NotImplementedError
 
     def render_pyout(self, cell):
+        """convert pyout part of a code cell
+
+        Returns list."""
         raise NotImplementedError
 
     def render_display_data(self, cell):
+        """convert display data from the output of a code cell
+
+        Returns list.
+        """
         raise NotImplementedError
 
     def render_stream(self, cell):
+        """convert stream part of a code cell
+
+        Returns list."""
+        raise NotImplementedError
+
+    def render_plaintext(self, cell):
+        """convert plain text
+
+        Returns list."""
         raise NotImplementedError
 
 
@@ -111,18 +136,13 b' class ConverterRST(Converter):'
     figures_counter = 0
     heading_level = {1: '=', 2: '-', 3: '`', 4: '\'', 5: '.', 6: '~'}
 
+    @DocInherit
     def render_heading(self, cell):
-        """convert a heading cell to rst
-
-        Returns list."""
         marker = self.heading_level[cell.level]
         return ['{0}\n{1}\n'.format(cell.source, marker * len(cell.source))]
 
+    @DocInherit
     def render_code(self, cell):
-        """Convert a code cell to rst
-
-        Returns list."""
-
         if not cell.input:
             return []
 
@@ -132,26 +152,19 b' class ConverterRST(Converter):'
         for output in cell.outputs:
             conv_fn = self.dispatch(output.output_type)
             lines.extend(conv_fn(output))
-        
+
         return lines
 
+    @DocInherit
     def render_markdown(self, cell):
-        """convert a markdown cell to rst
-
-        Returns list."""
         return [cell.source]
 
+    @DocInherit
     def render_plaintext(self, cell):
-        """convert plain text to rst
-
-        Returns list."""
         return [cell.source]
 
+    @DocInherit
     def render_pyout(self, output):
-        """convert pyout part of a code cell to rst
-
-        Returns list."""
-
         lines = ['Out[%s]:' % output.prompt_number, '']
 
         # output is a dictionary like object with type as a key
@@ -163,11 +176,8 b' class ConverterRST(Converter):'
 
         return lines
 
+    @DocInherit
     def render_display_data(self, output):
-        """convert display data from the output of a code cell to rst.
-
-        Returns list.
-        """
         lines = []
 
         if 'png' in output:
@@ -182,11 +192,8 b' class ConverterRST(Converter):'
 
         return lines
 
+    @DocInherit
     def render_stream(self, output):
-        """convert stream part of a code cell to rst
-
-        Returns list."""
-
         lines = []
 
         if 'text' in output: