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

@@ -1,271 +1,278 b''
 #!/usr/bin/env python
 """A really simple notebook to rst/html exporter.
 
 Usage
 
   ./nb2html.py file.ipynb
 
 Produces 'file.rst' and 'file.html', along with auto-generated figure files
 called nb_figure_NN.png.
 
 """
 
 import os
 import subprocess
 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
 
 def unknown_cell(cell):
     """Default converter for cells of unknown type.
     """
 
     return rst_directive('.. warning:: Unknown cell') + \
       [repr(cell)]
 
 
 def rst_directive(directive, text=''):
     out = [directive, '']
     if text:
         out.extend([indent(text), ''])
     return out
 
 # Converters for parts of a cell.
 
 
 class ConversionException(Exception):
     pass
 
 
 class Converter(object):
     default_encoding = 'utf-8'
 
     def __init__(self, infile):
         self.infile = infile
         self.dirpath = os.path.dirname(infile)
 
     @property
     def extension(self):
         raise ConversionException("""extension must be defined in Converter
                 subclass""")
 
     def dispatch(self, cell_type):
         """return cell_type dependent render method,  for example render_code
         """
         return getattr(self, 'render_' + cell_type, unknown_cell)
 
     def convert(self):
         lines = []
         for cell in self.nb.worksheets[0].cells:
             conv_fn = self.dispatch(cell.cell_type)
             lines.extend(conv_fn(cell))
             lines.append('')
         return '\n'.join(lines)
 
     def render(self):
         "read, convert, and save self.infile"
         self.read()
         self.output = self.convert()
         return self.save()
 
     def read(self):
         "read and parse notebook into NotebookNode called self.nb"
         with open(self.infile) as f:
             self.nb = nbformat.read(f, 'json')
 
     def save(self, infile=None, encoding=None):
         "read and parse notebook into self.nb"
         if infile is None:
             infile = os.path.splitext(self.infile)[0] + '.' + self.extension
         if encoding is None:
             encoding = self.default_encoding
         with open(infile, 'w') as f:
             f.write(self.output.encode(encoding))
         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
 
 
 class ConverterRST(Converter):
     extension = 'rst'
     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 []
 
         lines = ['In[%s]:' % cell.prompt_number, '']
         lines.extend(rst_directive('.. code:: python', cell.input))
 
         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
         if 'latex' in output:
             lines.extend(rst_directive('.. math::', output.latex))
 
         if 'text' in output:
             lines.extend(rst_directive('.. parsed-literal::', output.text))
 
         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:
             infile = 'nb_figure_%s.png' % self.figures_counter
             fullname = os.path.join(self.dirpath, infile)
             with open(fullname, 'w') as f:
                 f.write(output.png.decode('base64'))
 
             self.figures_counter += 1
             lines.append('.. image:: %s' % infile)
             lines.append('')
 
         return lines
 
+    @DocInherit
     def render_stream(self, output):
-        """convert stream part of a code cell to rst
-
-        Returns list."""
-
         lines = []
 
         if 'text' in output:
             lines.extend(rst_directive('.. parsed-literal::', output.text))
 
         return lines
 
 
 def rst2simplehtml(infile):
     """Convert a rst file to simplified html suitable for blogger.
 
     This just runs rst2html with certain parameters to produce really simple
     html and strips the document header, so the resulting file can be easily
     pasted into a blogger edit window.
     """
 
     # This is the template for the rst2html call that produces the cleanest,
     # simplest html I could find.  This should help in making it easier to
     # paste into the blogspot html window, though I'm still having problems
     # with linebreaks there...
     cmd_template = ("rst2html --link-stylesheet --no-xml-declaration "
                     "--no-generator --no-datestamp --no-source-link "
                     "--no-toc-backlinks --no-section-numbering "
                     "--strip-comments ")
 
     cmd = "%s %s" % (cmd_template, infile)
     proc = subprocess.Popen(cmd,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE,
                             shell=True)
     html, stderr = proc.communicate()
     if stderr:
         raise IOError(stderr)
 
     # Make an iterator so breaking out holds state.  Our implementation of
     # searching for the html body below is basically a trivial little state
     # machine, so we need this.
     walker = iter(html.splitlines())
 
     # Find start of main text, break out to then print until we find end /div.
     # This may only work if there's a real title defined so we get a 'div class'
     # tag, I haven't really tried.
     for line in walker:
         if line.startswith('<body>'):
             break
 
     newfname = os.path.splitext(infile)[0] + '.html'
     with open(newfname, 'w') as f:
         for line in walker:
             if line.startswith('</body>'):
                 break
             f.write(line)
             f.write('\n')
 
     return newfname
 
 
 def main(infile, format='rst'):
     """Convert a notebook to html in one step"""
     if format == 'rst':
         converter = ConverterRST(infile)
         converter.render()
     elif format == 'html':
         #Currently, conversion to html is a 2 step process, nb->rst->html
         converter = ConverterRST(infile)
         rstfname = converter.render()
         rst2simplehtml(rstfname)
 
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(description='nbconvert: Convert IPython notebooks to other formats')
 
     # TODO: consider passing file like object around, rather than filenames
     # would allow us to process stdin, or even http streams
     #parser.add_argument('infile', nargs='?', type=argparse.FileType('r'), default=sys.stdin)
 
     #Require a filename as a positional argument
     parser.add_argument('infile', nargs=1)
     parser.add_argument('-f', '--format', default='rst',
                         help='Output format. Supported formats: rst (default), html.')
     args = parser.parse_args()
     main(infile=args.infile[0], format=args.format)