def __init__(self, msg, argument=None, onion_txt=None):
"""
Parameters
----------
msg : str
The error message to be displayed.
argument : str, optional
The argument responsible for the error. if `None` (default),
determines the argument name from `msg`, which will be the
error message from an `argparse.ArgumentError` instance.
onion_txt : str, optional
The text of the installer arguments from onion comment in
which the error occurred (i.e., the full onion comment with
`# <installer>:` removed). If `None` (default), the error
will not be displayed in Python's `SyntaxError`-specific
traceback format.
"""
if (msg is not None and argument is None
and msg.startswith('argument ')):
split_msg = msg.split()
argument = split_msg[1].rstrip(':')
msg = ' '.join(split_msg[2:])
if (onion_txt is not None) and (argument is not None):
# default sorting is alphabetical where '--a' comes before
# '-a', so long option name will always be checked first,
# which is what we want
for aname in sorted(argument.split('/')):
if aname in onion_txt:
target_offset = onion_txt.index(aname)
break
else:
target_offset = 0
else:
target_offset = 0
# both `argparse.ArgumentError` and `SyntaxError` are
# non-cooperative, so need to initialize them separately rather
# than just running through the MRO via a call to super()
ArgumentError.__init__(self, argument=None, message=msg)
OnionParserError.__init__(self,
msg=msg,
target_text=onion_txt,
target_offset=target_offset)
self.argument_name = argument
