no longer need separate v4.compose

put it back in nbbase, and work around circular import another way

IPython/nbformat/v4/__init__.py

@@ -6,9 +6,6 b''
 from .nbbase import (
     NotebookNode,
     nbformat, nbformat_minor, nbformat_schema,
-)
-
-from .compose import (
     new_code_cell, new_heading_cell, new_markdown_cell, new_notebook,
     new_output,
 )

IPython/nbformat/v4/nbbase.py

@@ -1,4 +1,4 b''
-"""The basic dict based notebook format.
+"""Python API for composing notebook elements
 
 The Python representation of a notebook is a nested structure of
 dictionary subclasses that support attribute access
@@ -9,22 +9,21 b' helpers to build the structs in the right form.'
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-import pprint
-import uuid
-
 from IPython.utils.ipstruct import Struct
-from IPython.utils.py3compat import cast_unicode, unicode_type
-
 
 # Change this when incrementing the nbformat version
 nbformat = 4
 nbformat_minor = 0
 nbformat_schema = 'nbformat.v4.schema.json'
 
+def validate(node, ref=None):
+    """validate a v4 node"""
+    from ..current import validate
+    return validate(node, ref=ref, version=nbformat)
+
 class NotebookNode(Struct):
     pass
 
-
 def from_dict(d):
     if isinstance(d, dict):
         newd = NotebookNode()
@@ -36,3 +35,62 b' def from_dict(d):'
     else:
         return d
 
+
+def new_output(output_type, mime_bundle=None, **kwargs):
+    """Create a new output, to go in the ``cell.outputs`` list of a code cell."""
+    output = NotebookNode(output_type=output_type, **kwargs)
+    if mime_bundle:
+        output.update(mime_bundle)
+    # populate defaults:
+    output.setdefault('metadata', NotebookNode())
+    if output_type == 'stream':
+        output.setdefault('stream', 'stdout')
+        output.setdefault('text', '')
+    validate(output, output_type)
+    return output
+
+def new_code_cell(source='', **kwargs):
+    """Create a new code cell"""
+    cell = NotebookNode(cell_type='code', source=source, **kwargs)
+    cell.setdefault('metadata', NotebookNode())
+    cell.setdefault('source', '')
+    cell.setdefault('prompt_number', None)
+    cell.setdefault('outputs', [])
+
+    validate(cell, 'code_cell')
+    return cell
+
+def new_markdown_cell(source='', **kwargs):
+    """Create a new markdown cell"""
+    cell = NotebookNode(cell_type='markdown', source=source, **kwargs)
+    cell.setdefault('metadata', NotebookNode())
+
+    validate(cell, 'markdown_cell')
+    return cell
+
+def new_heading_cell(source='', **kwargs):
+    """Create a new heading cell"""
+    cell = NotebookNode(cell_type='heading', source=source, **kwargs)
+    cell.setdefault('metadata', NotebookNode())
+    cell.setdefault('level', 1)
+
+    validate(cell, 'heading_cell')
+    return cell
+
+def new_raw_cell(source='', **kwargs):
+    """Create a new raw cell"""
+    cell = NotebookNode(cell_type='raw', source=source, **kwargs)
+    cell.setdefault('metadata', NotebookNode())
+
+    validate(cell, 'raw_cell')
+    return cell
+
+def new_notebook(**kwargs):
+    """Create a new notebook"""
+    nb = NotebookNode(**kwargs)
+    nb.nbformat = nbformat
+    nb.nbformat_minor = nbformat_minor
+    nb.setdefault('cells', [])
+    nb.setdefault('metadata', NotebookNode())
+    validate(nb)
+    return nb

IPython/nbformat/v4/tests/nbexamples.py

@@ -3,7 +3,7 b''
 import os
 from base64 import encodestring
 
-from ..compose import (
+from ..nbbase import (
     new_code_cell, new_heading_cell, new_markdown_cell, new_notebook,
     new_output, new_raw_cell
 )

IPython/nbformat/v4/tests/test_nbbase.py

@@ -3,8 +3,8 b''
 
 import nose.tools as nt
 
-from ..validator import isvalid, validate, ValidationError
-from ..compose import (
+from IPython.nbformat.validator import isvalid, validate, ValidationError
+from ..nbbase import (
     NotebookNode, nbformat,
     new_code_cell, new_heading_cell, new_markdown_cell, new_notebook,
     new_output, new_raw_cell,

IPython/nbformat/v4/tests/test_validate.py

@@ -10,8 +10,8 b' import nose.tools as nt'
 
 from IPython.nbformat.validator import validate, ValidationError
 from ..nbjson import reads
-from ..nbbase import nbformat
-from ..compose import (
+from ..nbbase import (
+    nbformat,
     new_code_cell, new_heading_cell, new_markdown_cell, new_notebook,
     new_output, new_raw_cell,
 )
@@ -125,6 +125,6 b' def test_invalid_raw_cell():'
 
 def test_sample_notebook():
     here = os.path.dirname(__file__)
-    with io.open(os.path.join(here, "v4-test.ipynb"), encoding='utf-8') as f:
+    with io.open(os.path.join(here, os.pardir, os.pardir, 'tests', "test4.ipynb"), encoding='utf-8') as f:
         nb = reads(f.read())
     validate4(nb)