Fixing minor issues with nbformat.

* Test suite passes.
* nbformat put into a single location for easy update.

IPython/nbformat/v3/__init__.py

@@ -1,4 +1,4 b''
-"""The main API for the v2 notebook format.
+"""The main API for the v3 notebook format.
 
 Authors:
 
@@ -19,7 +19,7 b' Authors:'
 from .nbbase import (
     NotebookNode,
     new_code_cell, new_text_cell, new_notebook, new_output, new_worksheet,
-    new_metadata, new_author, new_heading_cell
+    new_metadata, new_author, new_heading_cell, nbformat
 )
 
 from .nbjson import reads as reads_json, writes as writes_json

IPython/nbformat/v3/convert.py

@@ -27,7 +27,7 b' from IPython.nbformat import v2'
 #-----------------------------------------------------------------------------
 
 def convert_to_this_nbformat(nb, orig_version=2):
-    """Convert a notebook to the v2 format.
+    """Convert a notebook to the v3 format.
 
     Parameters
     ----------

IPython/nbformat/v3/nbbase.py

@@ -30,6 +30,9 b' from IPython.utils.ipstruct import Struct'
 # Code
 #-----------------------------------------------------------------------------
 
+# Change this when incrementing the nbformat version
+nbformat = 3
+
 class NotebookNode(Struct):
     pass
 
@@ -146,7 +149,7 b' def new_worksheet(name=None, cells=None):'
 def new_notebook(metadata=None, worksheets=None):
     """Create a notebook by name, id and a list of worksheets."""
     nb = NotebookNode()
-    nb.nbformat = 3
+    nb.nbformat = nbformat
     if worksheets is None:
         nb.worksheets = []
     else:

IPython/nbformat/v3/nbpy.py

@@ -20,7 +20,7 b' import re'
 from .rwbase import NotebookReader, NotebookWriter
 from .nbbase import (
     new_code_cell, new_text_cell, new_worksheet,
-    new_notebook, new_heading_cell
+    new_notebook, new_heading_cell, nbformat
 )
 
 #-----------------------------------------------------------------------------
@@ -151,7 +151,7 b' class PyWriter(NotebookWriter):'
 
     def writes(self, nb, **kwargs):
         lines = [u'# -*- coding: utf-8 -*-']
-        lines.extend([u'# <nbformat>2</nbformat>',''])
+        lines.extend([u'# <nbformat>%i</nbformat>' % nbformat,''])
         for ws in nb.worksheets:
             for cell in ws.cells:
                 if cell.cell_type == u'code':

IPython/nbformat/v3/tests/nbexamples.py

@@ -4,7 +4,7 b' from base64 import encodestring'
 from ..nbbase import (
     NotebookNode,
     new_code_cell, new_text_cell, new_worksheet, new_notebook, new_output,
-    new_metadata, new_author, new_heading_cell
+    new_metadata, new_author, new_heading_cell, nbformat
 )
 
 # some random base64-encoded *bytes*
@@ -92,7 +92,7 b' nb0 = new_notebook('
 )
 
 nb0_py = """# -*- coding: utf-8 -*-
-# <nbformat>2</nbformat>
+# <nbformat>%i</nbformat>
 
 # <htmlcell>
 
@@ -122,6 +122,6 b' a = numpy.random.rand(100)'
 
 print a
 
-"""
+""" % nbformat
 
 

IPython/nbformat/v3/tests/test_nbbase.py

@@ -3,7 +3,7 b' from unittest import TestCase'
 from ..nbbase import (
     NotebookNode,
     new_code_cell, new_text_cell, new_worksheet, new_notebook, new_output,
-    new_author, new_metadata, new_heading_cell
+    new_author, new_metadata, new_heading_cell, nbformat
 )
 
 class TestCell(TestCase):
@@ -102,7 +102,7 b' class TestNotebook(TestCase):'
         nb = new_notebook()
         self.assertEquals(nb.worksheets, [])
         self.assertEquals(nb.metadata, NotebookNode())
-        self.assertEquals(nb.nbformat,2)
+        self.assertEquals(nb.nbformat,nbformat)
 
     def test_notebook(self):
         worksheets = [new_worksheet(),new_worksheet()]
@@ -110,7 +110,7 b' class TestNotebook(TestCase):'
         nb = new_notebook(metadata=metadata,worksheets=worksheets)
         self.assertEquals(nb.metadata.name,u'foo')
         self.assertEquals(nb.worksheets,worksheets)
-        self.assertEquals(nb.nbformat,2)
+        self.assertEquals(nb.nbformat,nbformat)
 
 class TestMetadata(TestCase):