Backport PR #3960: Don't make sphinx a dependency for importing nbconvert

Just move the import so it doesn't fire unless sphinx is used.

Even though it's trivial, probably not for 1.0.

IPython/nbconvert/transformers/sphinx.py

@@ -1,264 +1,264 b''
 """Module that allows custom Sphinx parameters to be set on the notebook and
 on the 'other' object passed into Jinja.  Called prior to Jinja conversion
 process.
 """
 #-----------------------------------------------------------------------------
 # Copyright (c) 2013, the IPython Development Team.
 #
 # Distributed under the terms of the Modified BSD License.
 #
 # The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from __future__ import print_function, absolute_import
 
 # Stdlib imports
-# Used to find Sphinx package location
-import sphinx
 import os.path
 
 # Used to set the default date to today's date 
 from datetime import date 
 
 # Third-party imports
 # Needed for Pygments latex definitions.
 from pygments.formatters import LatexFormatter
 
 # Our own imports
 # Configurable traitlets
 from IPython.utils.traitlets import Unicode, Bool
 
 # Needed to override transformer
 from .base import (Transformer)
 
 from IPython.nbconvert.utils import console  
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 class SphinxTransformer(Transformer):
     """
     Sphinx utility transformer.
 
     This transformer is used to set variables needed by the latex to build
     Sphinx stylized templates.
     """
     
     interactive = Bool(False, config=True, help="""
         Allows you to define whether or not the Sphinx exporter will prompt
         you for input during the conversion process.  If this is set to false,
         the author, version, release, date, and chapter_style traits should
         be set.
         """)
     
     author = Unicode("Unknown Author", config=True, help="Author name")
     
     version = Unicode("", config=True, help="""
         Version number
         You can leave this blank if you do not want to render a version number.
         Example: "1.0.0"
         """)
     
     release = Unicode("", config=True, help="""
         Release name
         You can leave this blank if you do not want to render a release name.
         Example: "Rough Draft"
         """)
     
     publish_date = Unicode("", config=True, help="""
         Publish date
         This is the date to render on the document as the publish date.
         Leave this blank to default to todays date.  
         Example: "June 12, 1990"
         """)
     
     chapter_style = Unicode("Bjarne", config=True, help="""
         Sphinx chapter style
         This is the style to use for the chapter headers in the document.
         You may choose one of the following:
             "Bjarne"    (default)
             "Lenny"
             "Glenn"
             "Conny"
             "Rejne"
             "Sonny"    (used for international documents)
         """)
     
     output_style = Unicode("notebook", config=True, help="""
         Nbconvert Ipython
         notebook input/output formatting style.
         You may choose one of the following:
             "simple     (recommended for long code segments)"
             "notebook"  (default)
         """)
     
     center_output = Bool(False, config=True, help="""
         Optional attempt to center all output.  If this is false, no additional
         formatting is applied.
         """)
     
     use_headers = Bool(True, config=True, help="""
         Whether not a header should be added to the document.
         """)
     
     #Allow the user to override the title of the notebook (useful for
     #fancy document titles that the file system doesn't support.)
     overridetitle = Unicode("", config=True, help="")
 
     
     def call(self, nb, resources):
         """
         Sphinx transformation to apply on each notebook.
         
         Parameters
         ----------
         nb : NotebookNode
             Notebook being converted
         resources : dictionary
             Additional resources used in the conversion process.  Allows
             transformers to pass variables into the Jinja engine.
         """
+        # import sphinx here, so that sphinx is not a dependency when it's not used
+        import sphinx
          
         # TODO: Add versatile method of additional notebook metadata.  Include
         #       handling of multiple files.  For now use a temporay namespace,
         #       '_draft' to signify that this needs to change.
         if not "sphinx" in resources:
             resources["sphinx"] = {}
 
         if self.interactive:
             
             # Prompt the user for additional meta data that doesn't exist currently
             # but would be usefull for Sphinx.
             resources["sphinx"]["author"] = self._prompt_author()
             resources["sphinx"]["version"] = self._prompt_version()
             resources["sphinx"]["release"] = self._prompt_release()
             resources["sphinx"]["date"] = self._prompt_date()
             
             # Prompt the user for the document style.
             resources["sphinx"]["chapterstyle"] = self._prompt_chapter_title_style()
             resources["sphinx"]["outputstyle"] = self._prompt_output_style()
             
             # Small options
             resources["sphinx"]["centeroutput"] = console.prompt_boolean("Do you want to center the output? (false)", False)
             resources["sphinx"]["header"] = console.prompt_boolean("Should a Sphinx document header be used? (true)", True)
         else:
             
             # Try to use the traitlets.
             resources["sphinx"]["author"] = self.author
             resources["sphinx"]["version"] = self.version
             resources["sphinx"]["release"] = self.release
             
             # Use todays date if none is provided.
             if self.publish_date:
                 resources["sphinx"]["date"] = self.publish_date
             elif len(resources['metadata']['modified_date'].strip()) == 0:
                 resources["sphinx"]["date"] = date.today().strftime("%B %-d, %Y")
             else:
                 resources["sphinx"]["date"] = resources['metadata']['modified_date']
             
             # Sphinx traitlets.
             resources["sphinx"]["chapterstyle"] = self.chapter_style
             resources["sphinx"]["outputstyle"] = self.output_style
             resources["sphinx"]["centeroutput"] = self.center_output
             resources["sphinx"]["header"] = self.use_headers
             
         # Find and pass in the path to the Sphinx dependencies.
         resources["sphinx"]["texinputs"] = os.path.realpath(os.path.join(sphinx.package_dir, "texinputs"))
         
         # Generate Pygments definitions for Latex 
         resources["sphinx"]["pygment_definitions"] = self._generate_pygments_latex_def()
         
         if not (self.overridetitle == None or len(self.overridetitle.strip()) == 0):
             resources['metadata']['name'] = self.overridetitle
         
         # End
         return nb, resources 
     
     
     def _generate_pygments_latex_def(self):
         """
         Generate the pygments latex definitions that allows pygments
         to work in latex.
         """
         
         return LatexFormatter().get_style_defs()       
     
     
     def _prompt_author(self):
         """
         Prompt the user to input an Author name
         """
         return  console.input("Author name: ")
     
     
     def _prompt_version(self):
         """
         prompt the user to enter a version number
         """
         return  console.input("Version (ie ""1.0.0""): ")
     
     
     def _prompt_release(self):
         """
         Prompt the user to input a release name
         """
         
         return  console.input("Release Name (ie ""Rough draft""): ")
     
     
     def _prompt_date(self, resources):
         """
         Prompt the user to enter a date
         """
         
         if resources['metadata']['modified_date']:
             default_date = resources['metadata']['modified_date']
         else:
             default_date = date.today().strftime("%B %-d, %Y")
             
         user_date = console.input("Date (deafults to \"" + default_date + "\"): ")
         if len(user_date.strip()) == 0:
             user_date = default_date
         return user_date
     
     
     def _prompt_output_style(self):
         """
         Prompts the user to pick an IPython output style.
         """
         
         # Dictionary of available output styles
         styles = {1: "simple",
                   2: "notebook"}
         
         #Append comments to the menu when displaying it to the user.
         comments = {1: "(recommended for long code segments)",
                     2: "(default)"}
         
         return console.prompt_dictionary(styles, default_style=2, menu_comments=comments)
     
     
     def _prompt_chapter_title_style(self):
         """
         Prompts the user to pick a Sphinx chapter style
         """
         
         # Dictionary of available Sphinx styles
         styles = {1: "Bjarne",
                   2: "Lenny",
                   3: "Glenn",
                   4: "Conny",
                   5: "Rejne",
                   6: "Sonny"}
         
         #Append comments to the menu when displaying it to the user.
         comments = {1: "(default)",
                     6: "(for international documents)"}
         
         return console.prompt_dictionary(styles, menu_comments=comments)