Fixes "bugs with mutable defaults args", thanks @Carreau

IPython/nbconvert/exporters/exporter.py

@@ -1,361 +1,361 b''
 """This module defines Exporter, a highly configurable converter
 that uses Jinja2 to export notebook files into different formats.
 """
 
 #-----------------------------------------------------------------------------
 # 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
 import io
 import os
 import inspect
 import types
 from copy import deepcopy
 
 # other libs/dependencies
 from jinja2 import Environment, FileSystemLoader, ChoiceLoader
 
 # IPython imports
 from IPython.config.configurable import Configurable
 from IPython.config import Config
 from IPython.nbformat import current as nbformat
 from IPython.utils.traitlets import MetaHasTraits, DottedObjectName, Unicode, List, Dict
 from IPython.utils.importstring import import_item
 from IPython.utils.text import indent
 
 from IPython.nbconvert import filters
 from IPython.nbconvert import transformers
 
 #-----------------------------------------------------------------------------
 # Globals and constants
 #-----------------------------------------------------------------------------
 
 #Jinja2 extensions to load.
 JINJA_EXTENSIONS = ['jinja2.ext.loopcontrols']
 
 default_filters = {
         'indent': indent,
         'markdown': filters.markdown2html,
         'ansi2html': filters.ansi2html,
         'filter_data_type': filters.DataTypeFilter,
         'get_lines': filters.get_lines,
         'highlight': filters.highlight,
         'highlight2html': filters.highlight,
         'highlight2latex': filters.highlight2latex,
         'markdown2latex': filters.markdown2latex,
         'markdown2rst': filters.markdown2rst,
         'pycomment': filters.python_comment,
         'rm_ansi': filters.remove_ansi,
         'rm_dollars': filters.strip_dollars,
         'rm_fake': filters.rm_fake,
         'ansi2latex': filters.ansi2latex,
         'rm_math_space': filters.rm_math_space,
         'wrap': filters.wrap
 }
 
 #-----------------------------------------------------------------------------
 # Class
 #-----------------------------------------------------------------------------
 
 class Exporter(Configurable):
     """
     Exports notebooks into other file formats.  Uses Jinja 2 templating engine
     to output new formats.  Inherit from this class if you are creating a new
     template type along with new filters/transformers.  If the filters/
     transformers provided by default suffice, there is no need to inherit from
     this class.  Instead, override the template_file and file_extension
     traits via a config file.
     
     {filters}
     """
     
     # finish the docstring
     __doc__ = __doc__.format(filters = '- '+'\n    - '.join(default_filters.keys()))
 
 
     template_file = Unicode(
             '', config=True,
             help="Name of the template file to use")
 
     file_extension = Unicode(
         'txt', config=True, 
         help="Extension of the file that should be written to disk"
         )
 
     template_path = Unicode(
         os.path.join("..", "templates"), config=True,
         help="Path where the template files are located.")
 
     template_skeleton_path = Unicode(
         os.path.join("..", "templates", "skeleton"), config=True,
         help="Path where the template skeleton files are located.") 
 
     #Jinja block definitions
     jinja_comment_block_start = Unicode("", config=True)
     jinja_comment_block_end = Unicode("", config=True)
     jinja_variable_block_start = Unicode("", config=True)
     jinja_variable_block_end = Unicode("", config=True)
     jinja_logic_block_start = Unicode("", config=True)
     jinja_logic_block_end = Unicode("", config=True)
     
     #Extension that the template files use.    
     template_extension = Unicode(".tpl", config=True)
 
     #Configurability, allows the user to easily add filters and transformers.
     transformers = List(config=True,
         help="""List of transformers, by name or namespace, to enable.""")
     filters = Dict(config=True,
         help="""Dictionary of filters, by name and namespace, to add to the Jinja
         environment.""")
     
     def __init__(self, config=None, extra_loaders=None, **kw):
         """
         Public constructor
     
         Parameters
         ----------
         config : config
             User configuration instance.
         extra_loaders : list[of Jinja Loaders]
             ordered list of Jinja loder to find templates. Will be tried in order
             before the default FileSysteme ones.
         """
         
         #Call the base class constructor
         c = self.default_config
         if config:
             c.merge(config)
 
         super(Exporter, self).__init__(config=c, **kw)
 
         #Standard environment
         self._init_environment(extra_loaders=extra_loaders)
 
         #Add transformers
         self._transformers = []
         self._register_transformers()
 
         #Add filters to the Jinja2 environment
         self._register_filters()
 
         #Load user transformers.  Enabled by default.
         if self.transformers:
             for transformer in self.transformers:
                 self.register_transformer(transformer, True)
                 
         #Load user filters.  Overwrite existing filters if need be.
         if self.filters:
             for key, user_filter in self.filters.iteritems():
                 self.register_filter(key, user_filter)
 
 
     @property
     def default_config(self):
         return Config()
 
     
-    def from_notebook_node(self, nb, resources={}, **kw):
+    def from_notebook_node(self, nb, resources=None, **kw):
         """
         Convert a notebook from a notebook node instance.
     
         Parameters
         ----------
         nb : Notebook node
         resources : dict (**kw) 
             of additional resources that can be accessed read/write by 
             transformers and filters.
         """
         nb_copy = deepcopy(nb)
 
         #Preprocess
         nb_copy, resources = self._preprocess(nb_copy, resources)
 
         #Convert
         self.template = self.environment.get_template(self.template_file + self.template_extension)
         output = self.template.render(nb=nb_copy, resources=resources)
 
         #Set output extension in resources dict
         resources['output_extension'] = self.file_extension
         return output, resources
 
 
-    def from_filename(self, filename, resources={}, **kw):
+    def from_filename(self, filename, resources=None **kw):
         """
         Convert a notebook from a notebook file.
     
         Parameters
         ----------
         filename : str
             Full filename of the notebook file to open and convert.
         """
         
         with io.open(filename) as f:
             return self.from_notebook_node(nbformat.read(f, 'json'), resources=resources,**kw)
 
 
-    def from_file(self, file_stream, resources={}, **kw):
+    def from_file(self, file_stream, resources=None, **kw):
         """
         Convert a notebook from a notebook file.
     
         Parameters
         ----------
         file_stream : file-like object
             Notebook file-like object to convert.
         """
         return self.from_notebook_node(nbformat.read(file_stream, 'json'), resources=resources, **kw)
 
 
     def register_transformer(self, transformer, enabled=None):
         """
         Register a transformer.
         Transformers are classes that act upon the notebook before it is
         passed into the Jinja templating engine.  Transformers are also
         capable of passing additional information to the Jinja
         templating engine.
     
         Parameters
         ----------
         transformer : transformer
         """
 
         #Handle transformer's registration based on it's type
         if inspect.isfunction(transformer):
             #Transformer is a function, no need to construct it.
             self._transformers.append(transformer)
             return transformer
 
         elif isinstance(transformer, types.StringTypes):
             #Transformer is a string, import the namespace and recursively call
             #this register_transformer method
             transformer_cls = import_item(DottedObjectName(transformer))
             return self.register_transformer(transformer_cls, enabled=None)
 
         elif isinstance(transformer, MetaHasTraits):
             #Transformer is configurable.  Make sure to pass in new default for 
             #the enabled flag if one was specified.
             c = Config()
             if not enabled is None:
                 c = Config({transformer.__name__: {'enabled': enabled}})
             c.merge(self.config)
             transformer_instance = transformer(config=c)
 
         else:
             #Transformer is not configurable, construct it
             transformer_instance = transformer()
 
         #Register and return the transformer.
         self._transformers.append(transformer_instance)
         return transformer_instance
 
 
     def register_filter(self, name, filter):
         """
         Register a filter.
         A filter is a function that accepts and acts on one string.  
         The filters are accesible within the Jinja templating engine.
     
         Parameters
         ----------
         name : str
             name to give the filter in the Jinja engine
         filter : filter
         """
         if inspect.isfunction(filter):
             self.environment.filters[name] = filter
         elif isinstance(filter, types.StringTypes):
             filter_cls = import_item(DottedObjectName(filter))
             self.register_filter(name, filter_cls)
         elif isinstance(filter, MetaHasTraits):
             self.environment.filters[name] = filter(config=self.config)
         else:
             self.environment.filters[name] = filter()
         return self.environment.filters[name]
 
     
     def _register_transformers(self):
         """
         Register all of the transformers needed for this exporter, disabled
         unless specified explicitly.
         """
 
         self.register_transformer(transformers.coalesce_streams)
         self.register_transformer(transformers.ExtractFigureTransformer)
         
         
     def _register_filters(self):
         """
         Register all of the filters required for the exporter.
         """
         for key, value in default_filters.iteritems():
             self.register_filter(key, value)
         
         
     def _init_environment(self, extra_loaders=None):
         """
         Create the Jinja templating environment.
         """
         here = os.path.dirname(os.path.realpath(__file__))
         loaders = []
         if extra_loaders:
             loaders.extend(extra_loaders)
 
         loaders.append(FileSystemLoader([
                 os.path.join(here, self.template_path),
                 os.path.join(here, self.template_skeleton_path),
                 ]))
 
         self.environment = Environment(
             loader= ChoiceLoader(loaders),
             extensions=JINJA_EXTENSIONS
             )
         
         #Set special Jinja2 syntax that will not conflict with latex.
         if self.jinja_logic_block_start:
             self.environment.block_start_string = self.jinja_logic_block_start
         if self.jinja_logic_block_end:
             self.environment.block_end_string = self.jinja_logic_block_end
         if self.jinja_variable_block_start:
             self.environment.variable_start_string = self.jinja_variable_block_start
         if self.jinja_variable_block_end:
             self.environment.variable_end_string = self.jinja_variable_block_end
         if self.jinja_comment_block_start:
             self.environment.comment_start_string = self.jinja_comment_block_start
         if self.jinja_comment_block_end:
             self.environment.comment_end_string = self.jinja_comment_block_end
 
 
     def _preprocess(self, nb, resources):
         """
         Preprocess the notebook before passing it into the Jinja engine.
         To preprocess the notebook is to apply all of the 
     
         Parameters
         ----------
         nb : notebook node
             notebook that is being exported.
         resources : a dict of additional resources that
             can be accessed read/write by transformers
             and filters.
         """
         
         # Do a deepcopy first, 
         # we are never safe enough with what the transformers could do.
         nbc =  deepcopy(nb)
         resc = deepcopy(resources)
 
         #Run each transformer on the notebook.  Carry the output along
         #to each transformer
         for transformer in self._transformers:
             nbc, resc = transformer(nbc, resc)
         return nbc, resc