old_contents: """String class.
  
  Represents a unicode string using a widget.
  """
  
  # Copyright (c) Jupyter Development Team.
  # Distributed under the terms of the Modified BSD License.
  
  from .widget import DOMWidget, CallbackDispatcher, register
  from traitlets import Unicode, Bool
  from .deprecated import DeprecatedClass
  
  
  class _String(DOMWidget):
      """Base class used to create widgets that represent a string."""
      value = Unicode(help="String value", sync=True)
      disabled = Bool(False, help="Enable or disable user changes", sync=True)
      description = Unicode(help="Description of the value this widget represents", sync=True)
      placeholder = Unicode("", help="Placeholder text to display when nothing has been typed", sync=True)
  
      def __init__(self, value=None, **kwargs):
          if value is not None:
              kwargs['value'] = value
          super(_String, self).__init__(**kwargs)
  
  @register('IPython.HTML')
  class HTML(_String):
      """Renders the string `value` as HTML."""
      _view_name = Unicode('HTMLView', sync=True)
  
  
  @register('IPython.Latex')
  class Latex(_String):
      """Renders math inside the string `value` as Latex (requires $ $ or $$ $$ 
      and similar latex tags)."""
      _view_name = Unicode('LatexView', sync=True)
  
  
  @register('IPython.Textarea')
  class Textarea(_String):
      """Multiline text area widget."""
      _view_name = Unicode('TextareaView', sync=True)
  
      def scroll_to_bottom(self):
          self.send({"method": "scroll_to_bottom"})
  
  
  @register('IPython.Text')
  class Text(_String):
      """Single line textbox widget."""
      _view_name = Unicode('TextView', sync=True)
  
      def __init__(self, *args, **kwargs):
          super(Text, self).__init__(*args, **kwargs)
          self._submission_callbacks = CallbackDispatcher()
          self.on_msg(self._handle_string_msg)
  
      def _handle_string_msg(self, _, content):
          """Handle a msg from the front-end.
  
          Parameters
          ----------
          content: dict
              Content of the msg."""
          if content.get('event', '') == 'submit':
              self._submission_callbacks(self)
  
      def on_submit(self, callback, remove=False):
          """(Un)Register a callback to handle text submission.
  
          Triggered when the user clicks enter.
  
          Parameters
          ----------
          callback: callable
              Will be called with exactly one argument: the Widget instance
          remove: bool (optional)
              Whether to unregister the callback"""
          self._submission_callbacks.register_callback(callback, remove=remove)
  
  
  # Remove in IPython 4.0
  HTMLWidget = DeprecatedClass(HTML, 'HTMLWidget')
  LatexWidget = DeprecatedClass(Latex, 'LatexWidget')
  TextareaWidget = DeprecatedClass(Textarea, 'TextareaWidget')
  TextWidget = DeprecatedClass(Text, 'TextWidget')
  
new_contents: """String class.
  
  Represents a unicode string using a widget.
  """
  
  # Copyright (c) Jupyter Development Team.
  # Distributed under the terms of the Modified BSD License.
  
  from .widget import DOMWidget, CallbackDispatcher, register
  from traitlets import Unicode, Bool
  from .deprecated import DeprecatedClass
  
  
  class _String(DOMWidget):
      """Base class used to create widgets that represent a string."""
      value = Unicode(help="String value", sync=True)
      disabled = Bool(False, help="Enable or disable user changes", sync=True)
      description = Unicode(help="Description of the value this widget represents", sync=True)
      placeholder = Unicode("", help="Placeholder text to display when nothing has been typed", sync=True)
  
      def __init__(self, value=None, **kwargs):
          if value is not None:
              kwargs['value'] = value
          super(_String, self).__init__(**kwargs)
  
  @register('IPython.HTML')
  class HTML(_String):
      """Renders the string `value` as HTML."""
      _view_name = Unicode('HTMLView', sync=True)
  
  
  @register('IPython.Latex')
  class Latex(_String):
      """Renders math inside the string `value` as Latex (requires $ $ or $$ $$ 
      and similar latex tags)."""
      _view_name = Unicode('LatexView', sync=True)
  
  
  @register('IPython.Textarea')
  class Textarea(_String):
      """Multiline text area widget."""
      _view_name = Unicode('TextareaView', sync=True)
  
      def scroll_to_bottom(self):
          self.send({"method": "scroll_to_bottom"})
  
  
  @register('IPython.Text')
  class Text(_String):
      """Single line textbox widget."""
      _view_name = Unicode('TextView', sync=True)
  
      def __init__(self, *args, **kwargs):
          super(Text, self).__init__(*args, **kwargs)
          self._submission_callbacks = CallbackDispatcher()
          self.on_msg(self._handle_string_msg)
  
      def _handle_string_msg(self, _, content, buffers):
          """Handle a msg from the front-end.
  
          Parameters
          ----------
          content: dict
              Content of the msg."""
          if content.get('event', '') == 'submit':
              self._submission_callbacks(self)
  
      def on_submit(self, callback, remove=False):
          """(Un)Register a callback to handle text submission.
  
          Triggered when the user clicks enter.
  
          Parameters
          ----------
          callback: callable
              Will be called with exactly one argument: the Widget instance
          remove: bool (optional)
              Whether to unregister the callback"""
          self._submission_callbacks.register_callback(callback, remove=remove)
  
  
  # Remove in IPython 4.0
  HTMLWidget = DeprecatedClass(HTML, 'HTMLWidget')
  LatexWidget = DeprecatedClass(Latex, 'LatexWidget')
  TextareaWidget = DeprecatedClass(Textarea, 'TextareaWidget')
  TextWidget = DeprecatedClass(Text, 'TextWidget')
  
subject: Add buffers argument to a widget custom message handler