pyparsing issue
Question: Right now I have just started to use `pyparsing` to parse simple postfix
expressions. At the moment, I got this far:

    
    
    from pyparsing import *
    integer = Word(nums)
    op = Word("+-*/^", max=1)
    space = Word(" ")
    expr = Word(nums)+space+Word(nums)+space+op
    parsed = expr.parseString("3 4 *")
    print parsed
    

But when I run it, it prints:

    
    
    Traceback (most recent call last):
      File "star_parse.py", line 6, in <module>
        parsed = expr.parseString("3 4 *")
      File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/pyparsing-1.5.5-py2.6.egg/pyparsing.py", line 1100, in parseString
        raise exc
    pyparsing.ParseException: Expected W:( ) (at char 2), (line:1, col:3)
    

What am I doing wrong?


Answer: White space is handled by default. There is also the handy `oneOf`:

    
    
    from pyparsing import *
    integer = Word(nums)
    op = oneOf('* + - / ^')
    expr = integer + integer + op
    parsed = expr.parseString("3 4 *")
    print parsed
    

