help(parse_tree) trigger an AssertionError

[mdamien]

I'm using the calc example:

  File "calc.py", line 125, in main
    help(parse_tree)
  File "/home/damien/.venv/lib/python3.6/site.py", line 505, in __call__
    return pydoc.help(*args, **kwds)
  File "/usr/lib/python3.6/pydoc.py", line 1864, in __call__
    self.help(request)
  File "/usr/lib/python3.6/pydoc.py", line 1923, in help
    else: doc(request, 'Help on %s:', output=self._output)
  File "/usr/lib/python3.6/pydoc.py", line 1650, in doc
    pager(render_doc(thing, title, forceload))
  File "/usr/lib/python3.6/pydoc.py", line 1625, in render_doc
    object, name = resolve(thing, forceload)
  File "/usr/lib/python3.6/pydoc.py", line 1617, in resolve
    name = getattr(thing, '__name__', None)
  File "../arpeggio/__init__.py", line 1170, in __getattr__
    result = NonTerminal(rule=rule, nodes=nodes, _filtered=True)
  File ".../arpeggio/__init__.py", line 1098, in __init__
    super(NonTerminal, self).__init__(rule, position, error)
  File ".../arpeggio/__init__.py", line 971, in __init__
    assert rule

It's also simply triggered by parse_tree.__name__

Looks like it's because parse_tree. is used to find a child and __name__ is not a child

Adding a simple __name__ method to NonTerminal fix the issue:

class NonTerminal(ParseTreeNode, list):
...
    def __name__(self):
        return 'test'

[igordejanovic]

Thanks for reporting. Actually, accessing any non-existing attribute on a parse tree node was leading to assertion error. With this fix it will be correctly handled by raising AttributeError.