parameters: (self, exc_tuple, handler)
docstring: set_custom_exc(exc_tuple, handler)
  
          Set a custom exception handler, which will be called if any of the
          exceptions in exc_tuple occur in the mainloop (specifically, in the
          run_code() method).
  
          Parameters
          ----------
  
          exc_tuple : tuple of exception classes
              A *tuple* of exception classes, for which to call the defined
              handler.  It is very important that you use a tuple, and NOT A
              LIST here, because of the way Python's except statement works.  If
              you only want to trap a single exception, use a singleton tuple::
  
                  exc_tuple == (MyCustomException,)
  
          handler : callable
              handler must have the following signature::
  
                  def my_handler(self, etype, value, tb, tb_offset=None):
                      ...
                      return structured_traceback
  
              Your handler must return a structured traceback (a list of strings),
              or None.
  
              This will be made into an instance method (via types.MethodType)
              of IPython itself, and it will be called if any of the exceptions
              listed in the exc_tuple are caught. If the handler is None, an
              internal basic one is used, which just prints basic info.
  
              To protect IPython from crashes, if your handler ever raises an
              exception or returns an invalid result, it will be immediately
              disabled.
  
          Notes
          -----
  
          WARNING: by putting in your own exception handler into IPython's main
          execution loop, you run a very good chance of nasty crashes.  This
          facility should only be used if you really know what you are doing.
docstring_summary: set_custom_exc(exc_tuple, handler)
docstring_tokens: set_custom_exc ( exc_tuple handler )
function: def set_custom_exc(self, exc_tuple, handler):
          """set_custom_exc(exc_tuple, handler)
  
          Set a custom exception handler, which will be called if any of the
          exceptions in exc_tuple occur in the mainloop (specifically, in the
          run_code() method).
  
          Parameters
          ----------
  
          exc_tuple : tuple of exception classes
              A *tuple* of exception classes, for which to call the defined
              handler.  It is very important that you use a tuple, and NOT A
              LIST here, because of the way Python's except statement works.  If
              you only want to trap a single exception, use a singleton tuple::
  
                  exc_tuple == (MyCustomException,)
  
          handler : callable
              handler must have the following signature::
  
                  def my_handler(self, etype, value, tb, tb_offset=None):
                      ...
                      return structured_traceback
  
              Your handler must return a structured traceback (a list of strings),
              or None.
  
              This will be made into an instance method (via types.MethodType)
              of IPython itself, and it will be called if any of the exceptions
              listed in the exc_tuple are caught. If the handler is None, an
              internal basic one is used, which just prints basic info.
  
              To protect IPython from crashes, if your handler ever raises an
              exception or returns an invalid result, it will be immediately
              disabled.
  
          Notes
          -----
  
          WARNING: by putting in your own exception handler into IPython's main
          execution loop, you run a very good chance of nasty crashes.  This
          facility should only be used if you really know what you are doing."""
          if not isinstance(exc_tuple, tuple):
              raise TypeError("The custom exceptions must be given as a tuple.")
  
          def dummy_handler(self, etype, value, tb, tb_offset=None):
              print('*** Simple custom exception handler ***')
              print('Exception type :', etype)
              print('Exception value:', value)
              print('Traceback      :', tb)
  
          def validate_stb(stb):
              """validate structured traceback return type
              
              return type of CustomTB *should* be a list of strings, but allow
              single strings or None, which are harmless.
              
              This function will *always* return a list of strings,
              and will raise a TypeError if stb is inappropriate.
              """
              msg = "CustomTB must return list of strings, not %r" % stb
              if stb is None:
                  return []
              elif isinstance(stb, str):
                  return [stb]
              elif not isinstance(stb, list):
                  raise TypeError(msg)
              # it's a list
              for line in stb:
                  # check every element
                  if not isinstance(line, str):
                      raise TypeError(msg)
              return stb
  
          if handler is None:
              wrapped = dummy_handler
          else:
              def wrapped(self,etype,value,tb,tb_offset=None):
                  """wrap CustomTB handler, to protect IPython from user code
  
                  This makes it harder (but not impossible) for custom exception
                  handlers to crash IPython.
                  """
                  try:
                      stb = handler(self,etype,value,tb,tb_offset=tb_offset)
                      return validate_stb(stb)
                  except:
                      # clear custom handler immediately
                      self.set_custom_exc((), None)
                      print("Custom TB Handler failed, unregistering", file=sys.stderr)
                      # show the exception in handler first
                      stb = self.InteractiveTB.structured_traceback(*sys.exc_info())
                      print(self.InteractiveTB.stb2text(stb))
                      print("The original exception:")
                      stb = self.InteractiveTB.structured_traceback(
                                              (etype,value,tb), tb_offset=tb_offset
                      )
                  return stb
  
          self.CustomTB = types.MethodType(wrapped,self)
          self.custom_exceptions = exc_tuple
function_tokens: def set_custom_exc ( self , exc_tuple , handler ) : if not isinstance ( exc_tuple , tuple ) : raise TypeError ( "The custom exceptions must be given as a tuple." ) def dummy_handler ( self , etype , value , tb , tb_offset = None ) : print ( '*** Simple custom exception handler ***' ) print ( 'Exception type :' , etype ) print ( 'Exception value:' , value ) print ( 'Traceback      :' , tb ) def validate_stb ( stb ) : """validate structured traceback return type
              
              return type of CustomTB *should* be a list of strings, but allow
              single strings or None, which are harmless.
              
              This function will *always* return a list of strings,
              and will raise a TypeError if stb is inappropriate.
              """ msg = "CustomTB must return list of strings, not %r" % stb if stb is None : return [ ] elif isinstance ( stb , str ) : return [ stb ] elif not isinstance ( stb , list ) : raise TypeError ( msg ) # it's a list for line in stb : # check every element if not isinstance ( line , str ) : raise TypeError ( msg ) return stb if handler is None : wrapped = dummy_handler else : def wrapped ( self , etype , value , tb , tb_offset = None ) : """wrap CustomTB handler, to protect IPython from user code
  
                  This makes it harder (but not impossible) for custom exception
                  handlers to crash IPython.
                  """ try : stb = handler ( self , etype , value , tb , tb_offset = tb_offset ) return validate_stb ( stb ) except : # clear custom handler immediately self . set_custom_exc ( ( ) , None ) print ( "Custom TB Handler failed, unregistering" , file = sys . stderr ) # show the exception in handler first stb = self . InteractiveTB . structured_traceback ( * sys . exc_info ( ) ) print ( self . InteractiveTB . stb2text ( stb ) ) print ( "The original exception:" ) stb = self . InteractiveTB . structured_traceback ( ( etype , value , tb ) , tb_offset = tb_offset ) return stb self . CustomTB = types . MethodType ( wrapped , self ) self . custom_exceptions = exc_tuple