[Pyparsing] Order problem in binary operation with operationPrecedence()

[Gustavo N. <me...@gu...>]

Hello again, everybody.

I've defined a Pyparsing grammar for boolean expressions, based on 
operationPrecedence() and I have an strange problem.

This grammar has five types of operands: 3 literals (string, number, set) and 
2 non-literals (variable, function).

The following expressions work like a charm:
 * "pi == 3.1416"
 * "pi > 3.1416"
 * "pi < 3.1416"
 * "pi => 3.1416"
 * "pi <= 3.1416"

But if I rearrange the operands, I'd get an exception (like "Expected end of 
text (at char 7), (line:1, col:8)"):
 * "3.1416 == pi"
 * "3.1416 < pi"
 * "3.1416 > pi"
 * etc.

Every other combination of operands work, AFAIK, except when the first operand 
in a binary operation is a number:
 * "hello" in {"hi", "bye", "hello", "good-bye"}
 * "e < pi"
 * "pi > e"

What's going wrong? I've attached an excerpt from my library for you to 
reproduce it easily.

Thanks in advance!
-- 
Gustavo Narea <xri://=Gustavo>.
| Tech blog: =Gustavo/(+blog)/tech  ~  About me: =Gustavo/about |