[Pyparsing] Possible bug with And._ErrorStop

[Johannes M. <Joh...@ne...>]

Hey there.

I am currently working on adding proper error handling to my parser and ran into a problem with the ErrorStop functionality of the And-class.

This works:
CaselessKeyword("foo") + "bar"

But using ErrorStop raises an AttributeError:
CaselessKeyword("foo") - "bar"

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/pyparsing.py", line 1384, in __repr__
    return _ustr(self)
  File "/usr/local/lib/python2.7/dist-packages/pyparsing.py", line 122, in _ustr
    return str(obj)
  File "/usr/local/lib/python2.7/dist-packages/pyparsing.py", line 2394, in __str__

  File "/usr/local/lib/python2.7/dist-packages/pyparsing.py", line 122, in _ustr
    return str(obj)
  File "/usr/local/lib/python2.7/dist-packages/pyparsing.py", line 1381, in __str__
    return self.name
  File "/usr/local/lib/python2.7/dist-packages/pyparsing.py", line 1424, in __getattr__
    raise AttributeError("no such attribute " + aname)
AttributeError: no such attribute name

This is because when "And.__sub__" initialises the "_ErrorStop" object "_ErrorStop.__init__" calls:

super(Empty, self).__init__(*args, **kwargs)

instead of:

super(_ErrorStop, self).__init__(*args, **kwargs)

So the constructor of "Empty", which is setting "name", will be skipped. I suppose that is not intended?

Best regards,

--
Johannes Meyer
Junior Application Developer

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