Prepend In [x] in traceback with "Input " to avoid messing doctest

parsing

IPython/core/ultratb.py

@@ -1,1132 +1,1132 b''
 # -*- coding: utf-8 -*-
 """
 Verbose and colourful traceback formatting.
 
 **ColorTB**
 
 I've always found it a bit hard to visually parse tracebacks in Python.  The
 ColorTB class is a solution to that problem.  It colors the different parts of a
 traceback in a manner similar to what you would expect from a syntax-highlighting
 text editor.
 
 Installation instructions for ColorTB::
 
     import sys,ultratb
     sys.excepthook = ultratb.ColorTB()
 
 **VerboseTB**
 
 I've also included a port of Ka-Ping Yee's "cgitb.py" that produces all kinds
 of useful info when a traceback occurs.  Ping originally had it spit out HTML
 and intended it for CGI programmers, but why should they have all the fun?  I
 altered it to spit out colored text to the terminal.  It's a bit overwhelming,
 but kind of neat, and maybe useful for long-running programs that you believe
 are bug-free.  If a crash *does* occur in that type of program you want details.
 Give it a shot--you'll love it or you'll hate it.
 
 .. note::
 
   The Verbose mode prints the variables currently visible where the exception
   happened (shortening their strings if too long). This can potentially be
   very slow, if you happen to have a huge data structure whose string
   representation is complex to compute. Your computer may appear to freeze for
   a while with cpu usage at 100%. If this occurs, you can cancel the traceback
   with Ctrl-C (maybe hitting it more than once).
 
   If you encounter this kind of situation often, you may want to use the
   Verbose_novars mode instead of the regular Verbose, which avoids formatting
   variables (but otherwise includes the information and context given by
   Verbose).
 
 .. note::
 
   The verbose mode print all variables in the stack, which means it can
   potentially leak sensitive information like access keys, or unencrypted
   password.
 
 Installation instructions for VerboseTB::
 
     import sys,ultratb
     sys.excepthook = ultratb.VerboseTB()
 
 Note:  Much of the code in this module was lifted verbatim from the standard
 library module 'traceback.py' and Ka-Ping Yee's 'cgitb.py'.
 
 Color schemes
 -------------
 
 The colors are defined in the class TBTools through the use of the
 ColorSchemeTable class. Currently the following exist:
 
   - NoColor: allows all of this module to be used in any terminal (the color
     escapes are just dummy blank strings).
 
   - Linux: is meant to look good in a terminal like the Linux console (black
     or very dark background).
 
   - LightBG: similar to Linux but swaps dark/light colors to be more readable
     in light background terminals.
 
   - Neutral: a neutral color scheme that should be readable on both light and
     dark background
 
 You can implement other color schemes easily, the syntax is fairly
 self-explanatory. Please send back new schemes you develop to the author for
 possible inclusion in future releases.
 
 Inheritance diagram:
 
 .. inheritance-diagram:: IPython.core.ultratb
    :parts: 3
 """
 
 #*****************************************************************************
 # Copyright (C) 2001 Nathaniel Gray <[e-mail]>
 # Copyright (C) 2001-2004 Fernando Perez <[e-mail]>
 #
 # Distributed under the terms of the BSD License.  The full license is in
 # the file COPYING, distributed as part of this software.
 #*****************************************************************************
 
 
 import inspect
 import linecache
 import pydoc
 import sys
 import time
 import traceback
 
 import stack_data
 from pygments.formatters.terminal256 import Terminal256Formatter
 from pygments.styles import get_style_by_name
 
 # IPython's own modules
 from IPython import get_ipython
 from IPython.core import debugger
 from IPython.core.display_trap import DisplayTrap
 from IPython.core.excolors import exception_colors
 from IPython.utils import path as util_path
 from IPython.utils import py3compat
 from IPython.utils.terminal import get_terminal_size
 
 import IPython.utils.colorable as colorable
 
 # Globals
 # amount of space to put line numbers before verbose tracebacks
 INDENT_SIZE = 8
 
 # Default color scheme.  This is used, for example, by the traceback
 # formatter.  When running in an actual IPython instance, the user's rc.colors
 # value is used, but having a module global makes this functionality available
 # to users of ultratb who are NOT running inside ipython.
 DEFAULT_SCHEME = 'NoColor'
 
 # ---------------------------------------------------------------------------
 # Code begins
 
 # Helper function -- largely belongs to VerboseTB, but we need the same
 # functionality to produce a pseudo verbose TB for SyntaxErrors, so that they
 # can be recognized properly by ipython.el's py-traceback-line-re
 # (SyntaxErrors have to be treated specially because they have no traceback)
 
 
 def _format_traceback_lines(lines, Colors, has_colors, lvals):
     """
     Format tracebacks lines with pointing arrow, leading numbers...
 
     Parameters
     ----------
     lines : list[Line]
     Colors
         ColorScheme used.
     lvals : str
         Values of local variables, already colored, to inject just after the error line.
     """
     numbers_width = INDENT_SIZE - 1
     res = []
 
     for stack_line in lines:
         if stack_line is stack_data.LINE_GAP:
             res.append('%s   (...)%s\n' % (Colors.linenoEm, Colors.Normal))
             continue
 
         line = stack_line.render(pygmented=has_colors).rstrip('\n') + '\n'
         lineno = stack_line.lineno
         if stack_line.is_current:
             # This is the line with the error
             pad = numbers_width - len(str(lineno))
             num = '%s%s' % (debugger.make_arrow(pad), str(lineno))
             start_color = Colors.linenoEm
         else:
             num = '%*s' % (numbers_width, lineno)
             start_color = Colors.lineno
 
         line = '%s%s%s %s' % (start_color, num, Colors.Normal, line)
 
         res.append(line)
         if lvals and stack_line.is_current:
             res.append(lvals + '\n')
     return res
 
 
 def _format_filename(file, ColorFilename, ColorNormal):
     """
     Format filename lines with `In [n]` if it's the nth code cell or `File *.py` if it's a module.
 
     Parameters
     ----------
     file : str
     ColorFilename
         ColorScheme's filename coloring to be used.
     ColorNormal
         ColorScheme's normal coloring to be used.
     """
     ipinst = get_ipython()
 
     if ipinst is not None and file in ipinst.compile._filename_map:
         file = "[%s]" % ipinst.compile._filename_map[file]
-        tpl_link = "In %s%%s%s" % (ColorFilename, ColorNormal)
+        tpl_link = "Input %sIn %%s%s" % (ColorFilename, ColorNormal)
     else:
         file = util_path.compress_user(
             py3compat.cast_unicode(file, util_path.fs_encoding)
         )
         tpl_link = "File %s%%s%s" % (ColorFilename, ColorNormal)
 
     return tpl_link % file
 
 #---------------------------------------------------------------------------
 # Module classes
 class TBTools(colorable.Colorable):
     """Basic tools used by all traceback printer classes."""
 
     # Number of frames to skip when reporting tracebacks
     tb_offset = 0
 
     def __init__(self, color_scheme='NoColor', call_pdb=False, ostream=None, parent=None, config=None):
         # Whether to call the interactive pdb debugger after printing
         # tracebacks or not
         super(TBTools, self).__init__(parent=parent, config=config)
         self.call_pdb = call_pdb
 
         # Output stream to write to.  Note that we store the original value in
         # a private attribute and then make the public ostream a property, so
         # that we can delay accessing sys.stdout until runtime.  The way
         # things are written now, the sys.stdout object is dynamically managed
         # so a reference to it should NEVER be stored statically.  This
         # property approach confines this detail to a single location, and all
         # subclasses can simply access self.ostream for writing.
         self._ostream = ostream
 
         # Create color table
         self.color_scheme_table = exception_colors()
 
         self.set_colors(color_scheme)
         self.old_scheme = color_scheme  # save initial value for toggles
 
         if call_pdb:
             self.pdb = debugger.Pdb()
         else:
             self.pdb = None
 
     def _get_ostream(self):
         """Output stream that exceptions are written to.
 
         Valid values are:
 
         - None: the default, which means that IPython will dynamically resolve
           to sys.stdout.  This ensures compatibility with most tools, including
           Windows (where plain stdout doesn't recognize ANSI escapes).
 
         - Any object with 'write' and 'flush' attributes.
         """
         return sys.stdout if self._ostream is None else self._ostream
 
     def _set_ostream(self, val):
         assert val is None or (hasattr(val, 'write') and hasattr(val, 'flush'))
         self._ostream = val
 
     ostream = property(_get_ostream, _set_ostream)
 
     def get_parts_of_chained_exception(self, evalue):
         def get_chained_exception(exception_value):
             cause = getattr(exception_value, '__cause__', None)
             if cause:
                 return cause
             if getattr(exception_value, '__suppress_context__', False):
                 return None
             return getattr(exception_value, '__context__', None)
 
         chained_evalue = get_chained_exception(evalue)
 
         if chained_evalue:
             return chained_evalue.__class__, chained_evalue, chained_evalue.__traceback__
 
     def prepare_chained_exception_message(self, cause):
         direct_cause = "\nThe above exception was the direct cause of the following exception:\n"
         exception_during_handling = "\nDuring handling of the above exception, another exception occurred:\n"
 
         if cause:
             message = [[direct_cause]]
         else:
             message = [[exception_during_handling]]
         return message
 
     @property
     def has_colors(self):
         return self.color_scheme_table.active_scheme_name.lower() != "nocolor"
 
     def set_colors(self, *args, **kw):
         """Shorthand access to the color table scheme selector method."""
 
         # Set own color table
         self.color_scheme_table.set_active_scheme(*args, **kw)
         # for convenience, set Colors to the active scheme
         self.Colors = self.color_scheme_table.active_colors
         # Also set colors of debugger
         if hasattr(self, 'pdb') and self.pdb is not None:
             self.pdb.set_colors(*args, **kw)
 
     def color_toggle(self):
         """Toggle between the currently active color scheme and NoColor."""
 
         if self.color_scheme_table.active_scheme_name == 'NoColor':
             self.color_scheme_table.set_active_scheme(self.old_scheme)
             self.Colors = self.color_scheme_table.active_colors
         else:
             self.old_scheme = self.color_scheme_table.active_scheme_name
             self.color_scheme_table.set_active_scheme('NoColor')
             self.Colors = self.color_scheme_table.active_colors
 
     def stb2text(self, stb):
         """Convert a structured traceback (a list) to a string."""
         return '\n'.join(stb)
 
     def text(self, etype, value, tb, tb_offset=None, context=5):
         """Return formatted traceback.
 
         Subclasses may override this if they add extra arguments.
         """
         tb_list = self.structured_traceback(etype, value, tb,
                                             tb_offset, context)
         return self.stb2text(tb_list)
 
     def structured_traceback(self, etype, evalue, tb, tb_offset=None,
                              context=5, mode=None):
         """Return a list of traceback frames.
 
         Must be implemented by each class.
         """
         raise NotImplementedError()
 
 
 #---------------------------------------------------------------------------
 class ListTB(TBTools):
     """Print traceback information from a traceback list, with optional color.
 
     Calling requires 3 arguments: (etype, evalue, elist)
     as would be obtained by::
 
       etype, evalue, tb = sys.exc_info()
       if tb:
         elist = traceback.extract_tb(tb)
       else:
         elist = None
 
     It can thus be used by programs which need to process the traceback before
     printing (such as console replacements based on the code module from the
     standard library).
 
     Because they are meant to be called without a full traceback (only a
     list), instances of this class can't call the interactive pdb debugger."""
 
     def __init__(self, color_scheme='NoColor', call_pdb=False, ostream=None, parent=None, config=None):
         TBTools.__init__(self, color_scheme=color_scheme, call_pdb=call_pdb,
                          ostream=ostream, parent=parent,config=config)
 
     def __call__(self, etype, value, elist):
         self.ostream.flush()
         self.ostream.write(self.text(etype, value, elist))
         self.ostream.write('\n')
 
     def _extract_tb(self, tb):
         if tb:
             return traceback.extract_tb(tb)
         else:
             return None
 
     def structured_traceback(self, etype, evalue, etb=None, tb_offset=None,
                              context=5):
         """Return a color formatted string with the traceback info.
 
         Parameters
         ----------
         etype : exception type
             Type of the exception raised.
         evalue : object
             Data stored in the exception
         etb : object
             If list: List of frames, see class docstring for details.
             If Traceback: Traceback of the exception.
         tb_offset : int, optional
             Number of frames in the traceback to skip.  If not given, the
             instance evalue is used (set in constructor).
         context : int, optional
             Number of lines of context information to print.
 
         Returns
         -------
         String with formatted exception.
         """
         # This is a workaround to get chained_exc_ids in recursive calls
         # etb should not be a tuple if structured_traceback is not recursive
         if isinstance(etb, tuple):
             etb, chained_exc_ids = etb
         else:
             chained_exc_ids = set()
 
         if isinstance(etb, list):
             elist = etb
         elif etb is not None:
             elist = self._extract_tb(etb)
         else:
             elist = []
         tb_offset = self.tb_offset if tb_offset is None else tb_offset
         Colors = self.Colors
         out_list = []
         if elist:
 
             if tb_offset and len(elist) > tb_offset:
                 elist = elist[tb_offset:]
 
             out_list.append('Traceback %s(most recent call last)%s:' %
                             (Colors.normalEm, Colors.Normal) + '\n')
             out_list.extend(self._format_list(elist))
         # The exception info should be a single entry in the list.
         lines = ''.join(self._format_exception_only(etype, evalue))
         out_list.append(lines)
 
         exception = self.get_parts_of_chained_exception(evalue)
 
         if exception and not id(exception[1]) in chained_exc_ids:
             chained_exception_message = self.prepare_chained_exception_message(
                 evalue.__cause__)[0]
             etype, evalue, etb = exception
             # Trace exception to avoid infinite 'cause' loop
             chained_exc_ids.add(id(exception[1]))
             chained_exceptions_tb_offset = 0
             out_list = (
                 self.structured_traceback(
                     etype, evalue, (etb, chained_exc_ids),
                     chained_exceptions_tb_offset, context)
                 + chained_exception_message
                 + out_list)
 
         return out_list
 
     def _format_list(self, extracted_list):
         """Format a list of traceback entry tuples for printing.
 
         Given a list of tuples as returned by extract_tb() or
         extract_stack(), return a list of strings ready for printing.
         Each string in the resulting list corresponds to the item with the
         same index in the argument list.  Each string ends in a newline;
         the strings may contain internal newlines as well, for those items
         whose source text line is not None.
 
         Lifted almost verbatim from traceback.py
         """
 
         Colors = self.Colors
         list = []
         for filename, lineno, name, line in extracted_list[:-1]:
             item = "  %s, line %s%d%s, in %s%s%s\n" % (
                 _format_filename(filename, Colors.filename, Colors.Normal),
                 Colors.lineno,
                 lineno,
                 Colors.Normal,
                 Colors.name,
                 name,
                 Colors.Normal,
             )
             if line:
                 item += '    %s\n' % line.strip()
             list.append(item)
         # Emphasize the last entry
         filename, lineno, name, line = extracted_list[-1]
         item = "%s  %s, line %s%d%s, in %s%s%s%s\n" % (
             Colors.normalEm,
             _format_filename(filename, Colors.filenameEm, Colors.normalEm),
             Colors.linenoEm,
             lineno,
             Colors.normalEm,
             Colors.nameEm,
             name,
             Colors.normalEm,
             Colors.Normal,
         )
         if line:
             item += '%s    %s%s\n' % (Colors.line, line.strip(),
                                       Colors.Normal)
         list.append(item)
         return list
 
     def _format_exception_only(self, etype, value):
         """Format the exception part of a traceback.
 
         The arguments are the exception type and value such as given by
         sys.exc_info()[:2]. The return value is a list of strings, each ending
         in a newline.  Normally, the list contains a single string; however,
         for SyntaxError exceptions, it contains several lines that (when
         printed) display detailed information about where the syntax error
         occurred.  The message indicating which exception occurred is the
         always last string in the list.
 
         Also lifted nearly verbatim from traceback.py
         """
         have_filedata = False
         Colors = self.Colors
         list = []
         stype = py3compat.cast_unicode(Colors.excName + etype.__name__ + Colors.Normal)
         if value is None:
             # Not sure if this can still happen in Python 2.6 and above
             list.append(stype + '\n')
         else:
             if issubclass(etype, SyntaxError):
                 have_filedata = True
                 if not value.filename: value.filename = "<string>"
                 if value.lineno:
                     lineno = value.lineno
                     textline = linecache.getline(value.filename, value.lineno)
                 else:
                     lineno = "unknown"
                     textline = ""
                 list.append(
                     "%s  %s, line %s%s%s\n"
                     % (
                         Colors.normalEm,
                         _format_filename(
                             value.filename, Colors.filenameEm, Colors.normalEm
                         ),
                         Colors.linenoEm,
                         lineno,
                         Colors.Normal,
                     )
                 )
                 if textline == "":
                     textline = py3compat.cast_unicode(value.text, "utf-8")
 
                 if textline is not None:
                     i = 0
                     while i < len(textline) and textline[i].isspace():
                         i += 1
                     list.append('%s    %s%s\n' % (Colors.line,
                                                   textline.strip(),
                                                   Colors.Normal))
                     if value.offset is not None:
                         s = '    '
                         for c in textline[i:value.offset - 1]:
                             if c.isspace():
                                 s += c
                             else:
                                 s += ' '
                         list.append('%s%s^%s\n' % (Colors.caret, s,
                                                    Colors.Normal))
 
             try:
                 s = value.msg
             except Exception:
                 s = self._some_str(value)
             if s:
                 list.append('%s%s:%s %s\n' % (stype, Colors.excName,
                                               Colors.Normal, s))
             else:
                 list.append('%s\n' % stype)
 
         # sync with user hooks
         if have_filedata:
             ipinst = get_ipython()
             if ipinst is not None:
                 ipinst.hooks.synchronize_with_editor(value.filename, value.lineno, 0)
 
         return list
 
     def get_exception_only(self, etype, value):
         """Only print the exception type and message, without a traceback.
 
         Parameters
         ----------
         etype : exception type
         value : exception value
         """
         return ListTB.structured_traceback(self, etype, value)
 
     def show_exception_only(self, etype, evalue):
         """Only print the exception type and message, without a traceback.
 
         Parameters
         ----------
         etype : exception type
         evalue : exception value
         """
         # This method needs to use __call__ from *this* class, not the one from
         # a subclass whose signature or behavior may be different
         ostream = self.ostream
         ostream.flush()
         ostream.write('\n'.join(self.get_exception_only(etype, evalue)))
         ostream.flush()
 
     def _some_str(self, value):
         # Lifted from traceback.py
         try:
             return py3compat.cast_unicode(str(value))
         except:
             return u'<unprintable %s object>' % type(value).__name__
 
 
 #----------------------------------------------------------------------------
 class VerboseTB(TBTools):
     """A port of Ka-Ping Yee's cgitb.py module that outputs color text instead
     of HTML.  Requires inspect and pydoc.  Crazy, man.
 
     Modified version which optionally strips the topmost entries from the
     traceback, to be used with alternate interpreters (because their own code
     would appear in the traceback)."""
 
     def __init__(self, color_scheme='Linux', call_pdb=False, ostream=None,
                  tb_offset=0, long_header=False, include_vars=True,
                  check_cache=None, debugger_cls = None,
                  parent=None, config=None):
         """Specify traceback offset, headers and color scheme.
 
         Define how many frames to drop from the tracebacks. Calling it with
         tb_offset=1 allows use of this handler in interpreters which will have
         their own code at the top of the traceback (VerboseTB will first
         remove that frame before printing the traceback info)."""
         TBTools.__init__(self, color_scheme=color_scheme, call_pdb=call_pdb,
                          ostream=ostream, parent=parent, config=config)
         self.tb_offset = tb_offset
         self.long_header = long_header
         self.include_vars = include_vars
         # By default we use linecache.checkcache, but the user can provide a
         # different check_cache implementation.  This is used by the IPython
         # kernel to provide tracebacks for interactive code that is cached,
         # by a compiler instance that flushes the linecache but preserves its
         # own code cache.
         if check_cache is None:
             check_cache = linecache.checkcache
         self.check_cache = check_cache
 
         self.debugger_cls = debugger_cls or debugger.Pdb
         self.skip_hidden = True
 
     def format_record(self, frame_info):
         """Format a single stack frame"""
         Colors = self.Colors  # just a shorthand + quicker name lookup
         ColorsNormal = Colors.Normal  # used a lot
 
         if isinstance(frame_info, stack_data.RepeatedFrames):
             return '    %s[... skipping similar frames: %s]%s\n' % (
                 Colors.excName, frame_info.description, ColorsNormal)
 
         indent = ' ' * INDENT_SIZE
         em_normal = '%s\n%s%s' % (Colors.valEm, indent, ColorsNormal)
         tpl_call = 'in %s%%s%s%%s%s' % (Colors.vName, Colors.valEm,
                                         ColorsNormal)
         tpl_call_fail = 'in %s%%s%s(***failed resolving arguments***)%s' % \
                         (Colors.vName, Colors.valEm, ColorsNormal)
         tpl_name_val = '%%s %s= %%s%s' % (Colors.valEm, ColorsNormal)
 
         link = _format_filename(frame_info.filename, Colors.filenameEm, ColorsNormal)
         args, varargs, varkw, locals_ = inspect.getargvalues(frame_info.frame)
 
         func = frame_info.executing.code_qualname()
         if func == '<module>':
             call = tpl_call % (func, '')
         else:
             # Decide whether to include variable details or not
             var_repr = eqrepr if self.include_vars else nullrepr
             try:
                 call = tpl_call % (func, inspect.formatargvalues(args,
                                                                  varargs, varkw,
                                                                  locals_, formatvalue=var_repr))
             except KeyError:
                 # This happens in situations like errors inside generator
                 # expressions, where local variables are listed in the
                 # line, but can't be extracted from the frame.  I'm not
                 # 100% sure this isn't actually a bug in inspect itself,
                 # but since there's no info for us to compute with, the
                 # best we can do is report the failure and move on.  Here
                 # we must *not* call any traceback construction again,
                 # because that would mess up use of %debug later on.  So we
                 # simply report the failure and move on.  The only
                 # limitation will be that this frame won't have locals
                 # listed in the call signature.  Quite subtle problem...
                 # I can't think of a good way to validate this in a unit
                 # test, but running a script consisting of:
                 #  dict( (k,v.strip()) for (k,v) in range(10) )
                 # will illustrate the error, if this exception catch is
                 # disabled.
                 call = tpl_call_fail % func
 
         lvals = ''
         lvals_list = []
         if self.include_vars:
             try:
                 # we likely want to fix stackdata at some point, but
                 # still need a workaround.
                 fibp = frame_info.variables_in_executing_piece
                 for var in fibp:
                     lvals_list.append(tpl_name_val % (var.name, repr(var.value)))
             except Exception:
                 lvals_list.append(
                     "Exception trying to inspect frame. No more locals available."
                 )
         if lvals_list:
             lvals = '%s%s' % (indent, em_normal.join(lvals_list))
 
         result = "%s, %s\n" % (link, call)
 
         result += ''.join(_format_traceback_lines(frame_info.lines, Colors, self.has_colors, lvals))
         return result
 
     def prepare_header(self, etype, long_version=False):
         colors = self.Colors  # just a shorthand + quicker name lookup
         colorsnormal = colors.Normal  # used a lot
         exc = '%s%s%s' % (colors.excName, etype, colorsnormal)
         width = min(75, get_terminal_size()[0])
         if long_version:
             # Header with the exception type, python version, and date
             pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable
             date = time.ctime(time.time())
 
             head = '%s%s%s\n%s%s%s\n%s' % (colors.topline, '-' * width, colorsnormal,
                                            exc, ' ' * (width - len(str(etype)) - len(pyver)),
                                            pyver, date.rjust(width) )
             head += "\nA problem occurred executing Python code.  Here is the sequence of function" \
                     "\ncalls leading up to the error, with the most recent (innermost) call last."
         else:
             # Simplified header
             head = '%s%s' % (exc, 'Traceback (most recent call last)'. \
                              rjust(width - len(str(etype))) )
 
         return head
 
     def format_exception(self, etype, evalue):
         colors = self.Colors  # just a shorthand + quicker name lookup
         colorsnormal = colors.Normal  # used a lot
         # Get (safely) a string form of the exception info
         try:
             etype_str, evalue_str = map(str, (etype, evalue))
         except:
             # User exception is improperly defined.
             etype, evalue = str, sys.exc_info()[:2]
             etype_str, evalue_str = map(str, (etype, evalue))
         # ... and format it
         return ['%s%s%s: %s' % (colors.excName, etype_str,
                                 colorsnormal, py3compat.cast_unicode(evalue_str))]
 
     def format_exception_as_a_whole(self, etype, evalue, etb, number_of_lines_of_context, tb_offset):
         """Formats the header, traceback and exception message for a single exception.
 
         This may be called multiple times by Python 3 exception chaining
         (PEP 3134).
         """
         # some locals
         orig_etype = etype
         try:
             etype = etype.__name__
         except AttributeError:
             pass
 
         tb_offset = self.tb_offset if tb_offset is None else tb_offset
         head = self.prepare_header(etype, self.long_header)
         records = self.get_records(etb, number_of_lines_of_context, tb_offset)
 
         frames = []
         skipped = 0
         lastrecord = len(records) - 1
         for i, r in enumerate(records):
             if not isinstance(r, stack_data.RepeatedFrames) and self.skip_hidden:
                 if r.frame.f_locals.get("__tracebackhide__", 0) and i != lastrecord:
                     skipped += 1
                     continue
             if skipped:
                 Colors = self.Colors  # just a shorthand + quicker name lookup
                 ColorsNormal = Colors.Normal  # used a lot
                 frames.append(
                     "    %s[... skipping hidden %s frame]%s\n"
                     % (Colors.excName, skipped, ColorsNormal)
                 )
                 skipped = 0
             frames.append(self.format_record(r))
         if skipped:
             Colors = self.Colors  # just a shorthand + quicker name lookup
             ColorsNormal = Colors.Normal  # used a lot
             frames.append(
                 "    %s[... skipping hidden %s frame]%s\n"
                 % (Colors.excName, skipped, ColorsNormal)
             )
 
         formatted_exception = self.format_exception(etype, evalue)
         if records:
             frame_info = records[-1]
             ipinst = get_ipython()
             if ipinst is not None:
                 ipinst.hooks.synchronize_with_editor(frame_info.filename, frame_info.lineno, 0)
 
         return [[head] + frames + [''.join(formatted_exception[0])]]
 
     def get_records(self, etb, number_of_lines_of_context, tb_offset):
         context = number_of_lines_of_context - 1
         after = context // 2
         before = context - after
         if self.has_colors:
             style = get_style_by_name('default')
             style = stack_data.style_with_executing_node(style, 'bg:#00005f')
             formatter = Terminal256Formatter(style=style)
         else:
             formatter = None
         options = stack_data.Options(
             before=before,
             after=after,
             pygments_formatter=formatter,
         )
         return list(stack_data.FrameInfo.stack_data(etb, options=options))[tb_offset:]
 
     def structured_traceback(self, etype, evalue, etb, tb_offset=None,
                              number_of_lines_of_context=5):
         """Return a nice text document describing the traceback."""
 
         formatted_exception = self.format_exception_as_a_whole(etype, evalue, etb, number_of_lines_of_context,
                                                                tb_offset)
 
         colors = self.Colors  # just a shorthand + quicker name lookup
         colorsnormal = colors.Normal  # used a lot
         head = '%s%s%s' % (colors.topline, '-' * min(75, get_terminal_size()[0]), colorsnormal)
         structured_traceback_parts = [head]
         chained_exceptions_tb_offset = 0
         lines_of_context = 3
         formatted_exceptions = formatted_exception
         exception = self.get_parts_of_chained_exception(evalue)
         if exception:
             formatted_exceptions += self.prepare_chained_exception_message(evalue.__cause__)
             etype, evalue, etb = exception
         else:
             evalue = None
         chained_exc_ids = set()
         while evalue:
             formatted_exceptions += self.format_exception_as_a_whole(etype, evalue, etb, lines_of_context,
                                                                      chained_exceptions_tb_offset)
             exception = self.get_parts_of_chained_exception(evalue)
 
             if exception and not id(exception[1]) in chained_exc_ids:
                 chained_exc_ids.add(id(exception[1])) # trace exception to avoid infinite 'cause' loop
                 formatted_exceptions += self.prepare_chained_exception_message(evalue.__cause__)
                 etype, evalue, etb = exception
             else:
                 evalue = None
 
         # we want to see exceptions in a reversed order:
         # the first exception should be on top
         for formatted_exception in reversed(formatted_exceptions):
             structured_traceback_parts += formatted_exception
 
         return structured_traceback_parts
 
     def debugger(self, force=False):
         """Call up the pdb debugger if desired, always clean up the tb
         reference.
 
         Keywords:
 
           - force(False): by default, this routine checks the instance call_pdb
             flag and does not actually invoke the debugger if the flag is false.
             The 'force' option forces the debugger to activate even if the flag
             is false.
 
         If the call_pdb flag is set, the pdb interactive debugger is
         invoked. In all cases, the self.tb reference to the current traceback
         is deleted to prevent lingering references which hamper memory
         management.
 
         Note that each call to pdb() does an 'import readline', so if your app
         requires a special setup for the readline completers, you'll have to
         fix that by hand after invoking the exception handler."""
 
         if force or self.call_pdb:
             if self.pdb is None:
                 self.pdb = self.debugger_cls()
             # the system displayhook may have changed, restore the original
             # for pdb
             display_trap = DisplayTrap(hook=sys.__displayhook__)
             with display_trap:
                 self.pdb.reset()
                 # Find the right frame so we don't pop up inside ipython itself
                 if hasattr(self, 'tb') and self.tb is not None:
                     etb = self.tb
                 else:
                     etb = self.tb = sys.last_traceback
                 while self.tb is not None and self.tb.tb_next is not None:
                     self.tb = self.tb.tb_next
                 if etb and etb.tb_next:
                     etb = etb.tb_next
                 self.pdb.botframe = etb.tb_frame
                 self.pdb.interaction(None, etb)
 
         if hasattr(self, 'tb'):
             del self.tb
 
     def handler(self, info=None):
         (etype, evalue, etb) = info or sys.exc_info()
         self.tb = etb
         ostream = self.ostream
         ostream.flush()
         ostream.write(self.text(etype, evalue, etb))
         ostream.write('\n')
         ostream.flush()
 
     # Changed so an instance can just be called as VerboseTB_inst() and print
     # out the right info on its own.
     def __call__(self, etype=None, evalue=None, etb=None):
         """This hook can replace sys.excepthook (for Python 2.1 or higher)."""
         if etb is None:
             self.handler()
         else:
             self.handler((etype, evalue, etb))
         try:
             self.debugger()
         except KeyboardInterrupt:
             print("\nKeyboardInterrupt")
 
 
 #----------------------------------------------------------------------------
 class FormattedTB(VerboseTB, ListTB):
     """Subclass ListTB but allow calling with a traceback.
 
     It can thus be used as a sys.excepthook for Python > 2.1.
 
     Also adds 'Context' and 'Verbose' modes, not available in ListTB.
 
     Allows a tb_offset to be specified. This is useful for situations where
     one needs to remove a number of topmost frames from the traceback (such as
     occurs with python programs that themselves execute other python code,
     like Python shells).  """
 
     def __init__(self, mode='Plain', color_scheme='Linux', call_pdb=False,
                  ostream=None,
                  tb_offset=0, long_header=False, include_vars=False,
                  check_cache=None, debugger_cls=None,
                  parent=None, config=None):
 
         # NEVER change the order of this list. Put new modes at the end:
         self.valid_modes = ['Plain', 'Context', 'Verbose', 'Minimal']
         self.verbose_modes = self.valid_modes[1:3]
 
         VerboseTB.__init__(self, color_scheme=color_scheme, call_pdb=call_pdb,
                            ostream=ostream, tb_offset=tb_offset,
                            long_header=long_header, include_vars=include_vars,
                            check_cache=check_cache, debugger_cls=debugger_cls,
                            parent=parent, config=config)
 
         # Different types of tracebacks are joined with different separators to
         # form a single string.  They are taken from this dict
         self._join_chars = dict(Plain='', Context='\n', Verbose='\n',
                                 Minimal='')
         # set_mode also sets the tb_join_char attribute
         self.set_mode(mode)
 
     def structured_traceback(self, etype, value, tb, tb_offset=None, number_of_lines_of_context=5):
         tb_offset = self.tb_offset if tb_offset is None else tb_offset
         mode = self.mode
         if mode in self.verbose_modes:
             # Verbose modes need a full traceback
             return VerboseTB.structured_traceback(
                 self, etype, value, tb, tb_offset, number_of_lines_of_context
             )
         elif mode == 'Minimal':
             return ListTB.get_exception_only(self, etype, value)
         else:
             # We must check the source cache because otherwise we can print
             # out-of-date source code.
             self.check_cache()
             # Now we can extract and format the exception
             return ListTB.structured_traceback(
                 self, etype, value, tb, tb_offset, number_of_lines_of_context
             )
 
     def stb2text(self, stb):
         """Convert a structured traceback (a list) to a string."""
         return self.tb_join_char.join(stb)
 
 
     def set_mode(self, mode=None):
         """Switch to the desired mode.
 
         If mode is not specified, cycles through the available modes."""
 
         if not mode:
             new_idx = (self.valid_modes.index(self.mode) + 1 ) % \
                       len(self.valid_modes)
             self.mode = self.valid_modes[new_idx]
         elif mode not in self.valid_modes:
             raise ValueError('Unrecognized mode in FormattedTB: <' + mode + '>\n'
                                                                             'Valid modes: ' + str(self.valid_modes))
         else:
             self.mode = mode
         # include variable details only in 'Verbose' mode
         self.include_vars = (self.mode == self.valid_modes[2])
         # Set the join character for generating text tracebacks
         self.tb_join_char = self._join_chars[self.mode]
 
     # some convenient shortcuts
     def plain(self):
         self.set_mode(self.valid_modes[0])
 
     def context(self):
         self.set_mode(self.valid_modes[1])
 
     def verbose(self):
         self.set_mode(self.valid_modes[2])
 
     def minimal(self):
         self.set_mode(self.valid_modes[3])
 
 
 #----------------------------------------------------------------------------
 class AutoFormattedTB(FormattedTB):
     """A traceback printer which can be called on the fly.
 
     It will find out about exceptions by itself.
 
     A brief example::
 
         AutoTB = AutoFormattedTB(mode = 'Verbose',color_scheme='Linux')
         try:
           ...
         except:
           AutoTB()  # or AutoTB(out=logfile) where logfile is an open file object
     """
 
     def __call__(self, etype=None, evalue=None, etb=None,
                  out=None, tb_offset=None):
         """Print out a formatted exception traceback.
 
         Optional arguments:
           - out: an open file-like object to direct output to.
 
           - tb_offset: the number of frames to skip over in the stack, on a
           per-call basis (this overrides temporarily the instance's tb_offset
           given at initialization time."""
 
         if out is None:
             out = self.ostream
         out.flush()
         out.write(self.text(etype, evalue, etb, tb_offset))
         out.write('\n')
         out.flush()
         # FIXME: we should remove the auto pdb behavior from here and leave
         # that to the clients.
         try:
             self.debugger()
         except KeyboardInterrupt:
             print("\nKeyboardInterrupt")
 
     def structured_traceback(self, etype=None, value=None, tb=None,
                              tb_offset=None, number_of_lines_of_context=5):
         if etype is None:
             etype, value, tb = sys.exc_info()
         if isinstance(tb, tuple):
             # tb is a tuple if this is a chained exception.
             self.tb = tb[0]
         else:
             self.tb = tb
         return FormattedTB.structured_traceback(
             self, etype, value, tb, tb_offset, number_of_lines_of_context)
 
 
 #---------------------------------------------------------------------------
 
 # A simple class to preserve Nathan's original functionality.
 class ColorTB(FormattedTB):
     """Shorthand to initialize a FormattedTB in Linux colors mode."""
 
     def __init__(self, color_scheme='Linux', call_pdb=0, **kwargs):
         FormattedTB.__init__(self, color_scheme=color_scheme,
                              call_pdb=call_pdb, **kwargs)
 
 
 class SyntaxTB(ListTB):
     """Extension which holds some state: the last exception value"""
 
     def __init__(self, color_scheme='NoColor', parent=None, config=None):
         ListTB.__init__(self, color_scheme, parent=parent, config=config)
         self.last_syntax_error = None
 
     def __call__(self, etype, value, elist):
         self.last_syntax_error = value
 
         ListTB.__call__(self, etype, value, elist)
 
     def structured_traceback(self, etype, value, elist, tb_offset=None,
                              context=5):
         # If the source file has been edited, the line in the syntax error can
         # be wrong (retrieved from an outdated cache). This replaces it with
         # the current value.
         if isinstance(value, SyntaxError) \
                 and isinstance(value.filename, str) \
                 and isinstance(value.lineno, int):
             linecache.checkcache(value.filename)
             newtext = linecache.getline(value.filename, value.lineno)
             if newtext:
                 value.text = newtext
         self.last_syntax_error = value
         return super(SyntaxTB, self).structured_traceback(etype, value, elist,
                                                           tb_offset=tb_offset, context=context)
 
     def clear_err_state(self):
         """Return the current error state and clear it"""
         e = self.last_syntax_error
         self.last_syntax_error = None
         return e
 
     def stb2text(self, stb):
         """Convert a structured traceback (a list) to a string."""
         return ''.join(stb)
 
 
 # some internal-use functions
 def text_repr(value):
     """Hopefully pretty robust repr equivalent."""
     # this is pretty horrible but should always return *something*
     try:
         return pydoc.text.repr(value)
     except KeyboardInterrupt:
         raise
     except:
         try:
             return repr(value)
         except KeyboardInterrupt:
             raise
         except:
             try:
                 # all still in an except block so we catch
                 # getattr raising
                 name = getattr(value, '__name__', None)
                 if name:
                     # ick, recursion
                     return text_repr(name)
                 klass = getattr(value, '__class__', None)
                 if klass:
                     return '%s instance' % text_repr(klass)
             except KeyboardInterrupt:
                 raise
             except:
                 return 'UNRECOVERABLE REPR FAILURE'
 
 
 def eqrepr(value, repr=text_repr):
     return '=%s' % repr(value)
 
 
 def nullrepr(value, repr=text_repr):
     return ''

docs/source/whatsnew/development.rst

@@ -1,437 +1,444 b''
 =====================
  Development version
 =====================
 
 This document describes in-flight development work.
 
 .. warning::
 
     Please do not edit this file by hand (doing so will likely cause merge
     conflicts for other Pull Requests). Instead, create a new file in the
     `docs/source/whatsnew/pr` folder
 
 
 Released .... ...., 2019
 
 
 Need to be updated:
 
 .. toctree::
    :maxdepth: 2
    :glob:
 
    pr/*
 
 IPython 8.0 is bringing a large number of new features and improvements to both the
 user of the terminal and of the kernel via Jupyter. The removal of compatibility
 with older version of Python is also the opportunity to do a couple of
 performance improvement in particular with respect to startup time.
 The 8.x branch started diverging from its predecessor around IPython 7.12
 (January 2020).
 
 This release contains 250+ Pull Requests, in addition to many of the features
 and backports that have made it to the 7.x branch. All PRs that went into this
 released are properly tagged with the 8.0 milestone if you wish to have a more
 in depth look at the changes.
 
 Please fell free to send pull-requests to updates those notes after release, 
 I have likely forgotten a few things reviewing 250+ PRs.
 
 Dependencies changes/downstream packaging
 -----------------------------------------
 
 Note that most of our building step have been changes to be (mostly) declarative
 and follow PEP 517, we are trying to completely remove ``setup.py`` (:ghpull:`13238`) and are
 looking for help to do so.
 
  - Minimum supported ``traitlets`` version if now 5+
  - we now require ``stack_data``
  - Minimal Python is now 3.8
  - ``nose`` is not a testing requirement anymore
  - ``pytest`` replaces nose.
  - ``iptest``/``iptest3`` cli entrypoints do not exists anymore. 
  - minimum officially support ``numpy`` version has been bumped, but this should
    not have much effect on packaging.
 
 
 Deprecation and removal
 -----------------------
 
 We removed almost all features, arguments, functions, and modules that were
 marked as deprecated between IPython 1.0 and 5.0. As reminder 5.0 was released
 in 2016, and 1.0 in 2013. Last release of the 5 branch was 5.10.0, in may 2020.
 The few remaining deprecated features we left have better deprecation warnings
 or have been turned into explicit errors for better error messages.
 
 I will use this occasion to add the following requests to anyone emitting a
 deprecation warning:
 
  - Please at at least ``stacklevel=2`` so that the warning is emitted into the
    caller context, and not the callee one.
  - Please add **since which version** something is deprecated.
 
 As a side note it is much easier to deal with conditional comparing to versions
 numbers than ``try/except`` when a functionality change with version. 
 
 I won't list all the removed features here, but modules like ``IPython.kernel``,
 which was just a shim module around ``ipykernel`` for the past 8 years have been
 remove, and so many other similar things that pre-date the name **Jupyter**
 itself.
 
 We no longer need to add ``IPyhton.extensions`` to the PYTHONPATH because that is being
 handled by ``load_extension``.
 
 We are also removing ``Cythonmagic``, ``sympyprinting`` and ``rmagic`` as they are now in
 other packages and no longer need to be inside IPython.
 
 
 Documentation
 -------------
 
 Majority of our docstrings have now been reformatted and automatically fixed by
 the experimental `Vélin <https://pypi.org/project/velin/>`_ project, to conform
 to numpydoc.
 
+Type annotations
+----------------
+
+While IPython itself is highly dynamic and can't be completely typed, many of
+the function now have type annotation, and part of the codebase and now checked
+by mypy.
+
 
 Featured changes
 ----------------
 
 Here is a features list of changes in IPython 8.0. This is of course non-exhaustive. 
 Please note as well that many features have been added in the 7.x branch as well
 (and hence why you want to read the 7.x what's new notes), in particular
 features contributed by QuantStack (with respect to debugger protocol, and Xeus
 Python), as well as many debugger features that I was please to implement as
 part of my work at QuanSight and Sponsored by DE Shaw.
 
 Better Tracebacks
 ~~~~~~~~~~~~~~~~~
 
 The first on is the integration of the ``stack_data`` package;
 which provide smarter informations in traceback; in particular it will highlight
 the AST node where an error occurs which can help to quickly narrow down errors.
 
 For example in the following snippet::
 
     def foo(i):
         x = [[[0]]]
         return x[0][i][0]
 
 
     def bar():
         return foo(0) + foo(
             1
         ) + foo(2)
 
 
 Calling ``bar()`` would raise an ``IndexError`` on the return line of ``foo``,
 IPython 8.0 is capable of telling you, where the index error occurs::
 
     return x[0][i][0]
                 ^
 Autosuggestons
 ~~~~~~~~~~~~~~
 
 Autosuggestion is a very useful feature available in `fish <https://fishshell.com/>`__, `zsh <https://en.wikipedia.org/wiki/Z_shell>`__, and `prompt-toolkit <https://python-prompt-toolkit.readthedocs.io/en/master/pages/asking_for_input.html#auto-suggestion>`__.
 
 `Ptpython <https://github.com/prompt-toolkit/ptpython#ptpython>`__ allows users to enable this feature in
 `ptpython/config.py <https://github.com/prompt-toolkit/ptpython/blob/master/examples/ptpython_config/config.py#L90>`__.
 
 This feature allows users to accept autosuggestions with ctrl e, ctrl f,
 or right arrow as described below.
 
 1. Start ipython
 
 .. image:: ../_images/8.0/auto_suggest_prompt_no_text.png
 
 2. Run ``print("hello")``
 
 .. image:: ../_images/8.0/auto_suggest_print_hello_suggest.png
 
 3. Press p to see the autosuggestion
 
 .. image:: ../_images/8.0/auto_suggest_print_hello_suggest.png
 
 4. Press ctrl f, or ctrl e, or right arrow to accept the suggestion
 
 .. image:: ../_images/8.0/auto_suggest_print_hello.png
 
 You can also complete word by word:
 
 1. Run ``def say_hello(): print("hello")``
 
 .. image:: ../_images/8.0/auto_suggest_second_prompt.png
 
 2. Press d to see the autosuggestion
 
 .. image:: ../_images/8.0/auto_suggest_d_phantom.png
 
 3. Press alt f to accept the first word of the suggestion
 
 .. image:: ../_images/8.0/auto_suggest_def_phantom.png
 
 Importantly, this feature does not interfere with tab completion:
 
 1. After running ``def say_hello(): print("hello")``, press d
 
 .. image:: ../_images/8.0/audo_suggest_d_phantom.png
 
 2. Press Tab to start tab completion
 
 .. image:: ../_images/8.0/auto_suggest_d_completions.png
 
 3A. Press Tab again to select the first option
 
 .. image:: ../_images/8.0/auto_suggest_def_completions.png
 
 3B. Press alt f to accept to accept the first word of the suggestion
 
 .. image:: ../_images/8.0/auto_suggest_def_phantom.png
 
 3C. Press ctrl f or ctrl e to accept the entire suggestion
 
 .. image:: ../_images/8.0/auto_suggest_match_parens.png
 
 To install a version of ipython with autosuggestions enabled, run:
 
 ``pip install git+https://github.com/mskar/ipython@auto_suggest``
 
 Currently, autosuggestions are only shown in the emacs or vi insert editing modes:
 
 - The ctrl e, ctrl f, and alt f shortcuts work by default in emacs mode.
 - To use these shortcuts in vi insert mode, you will have to create `custom keybindings in your config.py <https://github.com/mskar/setup/commit/2892fcee46f9f80ef7788f0749edc99daccc52f4/>`__.
 
 
 Show pinfo information in ipdb using "?" and "??"
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 In IPDB, it is now possible to show the information about an object using "?"
 and "??", in much the same way it can be done when using the IPython prompt::
 
     ipdb> partial?
     Init signature: partial(self, /, *args, **kwargs)
     Docstring:
     partial(func, *args, **keywords) - new function with partial application
     of the given arguments and keywords.
     File:           ~/.pyenv/versions/3.8.6/lib/python3.8/functools.py
     Type:           type
     Subclasses:
 
 Previously, "pinfo" or "pinfo2" command had to be used for this purpose.
 
 
 Autoreload 3 feature
 ~~~~~~~~~~~~~~~~~~~~
 
 Example: When an IPython session is ran with the 'autoreload' extension loaded,
 you will now have the option '3' to select which means the following:
 
     1. replicate all functionality from option 2
     2. autoload all new funcs/classes/enums/globals from the module when they're added
     3. autoload all newly imported funcs/classes/enums/globals from external modules
 
 Try ``%autoreload 3`` in an IPython session after running ``%load_ext autoreload``
 
 For more information please see unit test -
     extensions/tests/test_autoreload.py : 'test_autoload_newly_added_objects'
 
 
 
 
 History Range Glob feature
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Previously, when using ``%history``, users could specify either
 a range of sessions and lines, for example:
 
 .. code-block:: python
 
    ~8/1-~6/5   # see history from the first line of 8 sessions ago,
                # to the fifth line of 6 sessions ago.``
 
 Or users could specify a glob pattern:
 
 .. code-block:: python
 
    -g <pattern>  # glob ALL history for the specified pattern.
 
 However users could *not* specify both.
 
 If a user *did* specify both a range and a glob pattern,
 then the glob pattern would be used (globbing *all* history) *and the range would be ignored*.
 
 With this enhancement, if a user specifies both a range and a glob pattern, then the glob pattern will be applied to the specified range of history.
 
 Don't start a multi line cell with sunken parenthesis
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 From now on IPython will not ask for the next line of input when given a single
 line with more closing than opening brackets. For example, this means that if
 you (mis)type ']]' instead of '[]', a ``SyntaxError`` will show up, instead of
 the ``...:`` prompt continuation.
 
 IPython shell for ipdb interact
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 The ipdb ``interact`` starts an IPython shell instead of Python's built-in ``code.interact()``.
 
 Automatic Vi prompt stripping
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 When pasting code into IPython, it will strip the leading prompt characters if
 there are any. For example, you can paste the following code into the console -
 it will still work, even though each line is prefixed with prompts (`In`,
 `Out`)::
 
     In [1]: 2 * 2 == 4
     Out[1]: True
 
     In [2]: print("This still works as pasted")
 
 
 Previously, this was not the case for the Vi-mode prompts::
 
     In [1]: [ins] In [13]: 2 * 2 == 4
        ...: Out[13]: True
        ...:
       File "<ipython-input-1-727bb88eaf33>", line 1
         [ins] In [13]: 2 * 2 == 4
               ^
     SyntaxError: invalid syntax
 
 This is now fixed, and Vi prompt prefixes - ``[ins]`` and ``[nav]`` -  are
 skipped just as the normal ``In`` would be.
 
 IPython shell can be started in the Vi mode using ``ipython
 --TerminalInteractiveShell.editing_mode=vi``
 
 Empty History Ranges
 ~~~~~~~~~~~~~~~~~~~~
 
 A number of magics that take history ranges can now be used with an empty
 range. These magics are:
 
  * ``%save``
  * ``%load``
  * ``%pastebin``
  * ``%pycat``
 
 Using them this way will make them take the history of the current session up
 to the point of the magic call (such that the magic itself will not be
 included).
 
 Therefore it is now possible to save the whole history to a file using simple
 ``%save <filename>``, load and edit it using ``%load`` (makes for a nice usage
 when followed with :kbd:`F2`), send it to dpaste.org using ``%pastebin``, or
 view the whole thing syntax-highlighted with a single ``%pycat``.
 
 Traceback improvements
 ~~~~~~~~~~~~~~~~~~~~~~
 
 
 UPDATE THIS IN INPUT.
 
 Previously, error tracebacks for errors happening in code cells were showing a hash, the one used for compiling the Python AST::
 
     In [1]: def foo():
     ...:     return 3 / 0
     ...:
 
     In [2]: foo()
     ---------------------------------------------------------------------------
     ZeroDivisionError                         Traceback (most recent call last)
     <ipython-input-2-c19b6d9633cf> in <module>
     ----> 1 foo()
 
     <ipython-input-1-1595a74c32d5> in foo()
         1 def foo():
     ----> 2     return 3 / 0
         3
 
     ZeroDivisionError: division by zero
 
 The error traceback is now correctly formatted, showing the cell number in which the error happened::
 
     In [1]: def foo():
     ...:     return 3 / 0
     ...:
 
-    In [2]: foo()
+    Input In [2]: foo()
     ---------------------------------------------------------------------------
     ZeroDivisionError                         Traceback (most recent call last)
-    In [2], in <module>
+    input In [2], in <module>
     ----> 1 foo()
 
-    In [1], in foo()
+    Input In [1], in foo()
         1 def foo():
     ----> 2     return 3 / 0
 
     ZeroDivisionError: division by zero
 
 Miscellaneous
 ~~~~~~~~~~~~~
 
  - ``~`` is now expanded when part of a path in most magics :ghpull:`13385`
  - ``%/%%timeit`` magic now adds comma every thousands to make reading long number easier :ghpull:`13379`
  - ``"info"`` messages can now be customised to hide some fields :ghpull:`13343`
  - ``collections.UserList`` now pretty-prints :ghpull:`13320`
  - The debugger now have a persistent history, which should make it less
    annoying to retype commands :ghpull:`13246`
  - ``!pip`` ``!conda`` ``!cd`` or ``!ls`` are likely doing the wrong thing, we
    now warn users if they use it. :ghpull:`12954`
  - make ``%precision`` work for ``numpy.float64`` type :ghpull:`12902`
 
 
 
 
 Numfocus Small Developer Grant
 ------------------------------
 
 To prepare for Python 3.10 we have also started working on removing reliance and
 any dependency that is not Python 3.10 compatible; that include migrating our
 test suite to pytest, and starting to remove nose. This also mean that the
 ``iptest`` command is now gone, and all testing is via pytest.
 
 This was in bog part thanks the NumFOCUS Small Developer grant, we were able to
 allocate 4000 to hire `Nikita Kniazev @Kojoley <https://github.com/Kojoley>`__
 who did a fantastic job at updating our code base, migrating to pytest, pushing
 our coverage, and fixing a large number of bugs. I highly recommend contacting
 them if you need help with C++ and Python projects
 
 You can find all relevant issues and PRs with the SDG 2021 tag:
 
 https://github.com/ipython/ipython/issues?q=label%3A%22Numfocus+SDG+2021%22+
 
 Removing support for Older Python
 ---------------------------------
 
 
 We are also removing support for Python up to 3.7 allowing internal code to use more
 efficient ``pathlib``, and make better use of type annotations. 
 
 .. image:: ../_images/8.0/pathlib_pathlib_everywhere.jpg
    :alt: "Meme image of Toy story with Woody and Buzz, with the text 'pathlib, pathlib everywhere'"
 
 
 IMAGE : Pathlib, pathlib everywhere.
 
 We have about 34 PRs only to update some logic tu update some function from managing strings to
 using Pathlib.
 
 The completer has also seen significant updates and make use of newer Jedi API
 offering faster and more reliable tab completion.
 
 For the terminal users this also enable the auto-suggestion feature, described
 below, which show "ghost text" ahead of your cursor you can accept without
 having to press the tab key or ask the completer to suggest completions.
 
 
 
 .. DO NOT EDIT THIS LINE BEFORE RELEASE. FEATURE INSERTION POINT.
 
 As a reminder, IPython master has diverged from the 7.x branch, thus master may
 have more feature and API changes.
 
 Backwards incompatible changes
 ------------------------------
 
 .. DO NOT EDIT THIS LINE BEFORE RELEASE. INCOMPAT INSERTION POINT.