use nbconvert to write scripts

Author: akhmerov

jupyter_sphinx/execute.py

@@ -2,6 +2,7 @@
 
 import os
 from pathlib import Path
+from logging import Logger
 
 from sphinx.transforms import SphinxTransform
 from sphinx.errors import ExtensionError
@@ -40,6 +41,20 @@
 )
 
 
+class LoggerAdapterWrapper(Logger):
+    """Wrap a logger adapter, while pretending to be a logger.
+
+    Workaround of https://github.com/ipython/traitlets/issues/606
+    """
+    def __init__(self, wrapped):
+        self._wrapped = wrapped
+
+    def __getattribute__(self, attr):
+        if attr == "_wrapped":
+            return object.__getattribute__(self, attr)
+        return self._wrapped.__getattribute__(attr)
+
+
 class JupyterKernel(Directive):
     """Specify a new Jupyter Kernel.
 
@@ -262,20 +277,16 @@ def write_notebook_output(notebook, output_dir, notebook_name, location=None):
         resources,
         os.path.join(output_dir, notebook_name + ".ipynb"),
     )
-    # Write a script too.  Note that utf-8 is the de facto
-    # standard encoding for notebooks. 
-    ext = notebook.metadata.get("language_info", {}).get("file_extension", None)
-    if ext is None:
-        ext = ".txt"
-        js.logger.warning(
-            "Notebook code has no file extension metadata, " "defaulting to `.txt`",
-            location=location,
-        )
-    contents = "\n\n".join(cell.source for cell in notebook.cells)
 
-    notebook_file = notebook_name + ext
+    # Write a script too. Due to https://github.com/ipython/traitlets/issues/606
+    # we're using a wrapper to make a LoggerAdapter look like a wrapper.
+    exporter = nbconvert.exporters.ScriptExporter(log=LoggerAdapterWrapper(js.logger))
+    contents, resources = exporter.from_notebook_node(notebook)
+
+    notebook_file = notebook_name + resources['output_extension']
     output_dir = Path(output_dir)
-    (output_dir / notebook_file).write_text(contents, encoding = "utf8")
+    # utf-8 is the de-facto standard encoding for notebooks.
+    (output_dir / notebook_file).write_text(contents, encoding="utf8")
 
 
 def contains_widgets(notebook):

tests/test_execute.py

@@ -59,7 +59,6 @@ def doctree(
         app.build()
 
         doctree = app.env.get_and_resolve_doctree("index", app.builder)
-
         if return_warnings:
             return doctree, warnings.getvalue()
         else: