Re: [Pyparsing] How to distinguish a variable from a integer

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

Paul said:
> Ah, with that said, let me then suggest this as a starting point for
> implementing operand (assuming that variables can not start with a digit):
>
> LBRACE = Suppress('{')
> RBRACE = Suppress('}')
> operand = Forward()
> number = #...(as you have defined it in your original code)
> string_ = quotedString.setParseAction(removeQuotes)
> variable = #...(use your Unicode definition of choice)
> set_ = Group(LBRACE + delimitedList(operand) + RBRACE)
> operand << (number | string_ | variable | set_)
>
> delimitedList takes care of the repetition with intervening comma
> delimited. Group packages the result in its own list, so that recursive set
> definitions will maintain their nesting properly.  The set-enclosing braces
> are suppressed from the output - they are useful during parsing, but
> unnecessary once the tokens have been grouped.
>
> This is the canonical form for defining a recursive expression like your
> operand, mas o menos.  Now you are free to include operand in other
> expressions, or even operatorPrecedence.

Thank you very much for that! I was going to talk about that, because the way 
I implemented it was more complex and operand.validate() raised an exception.

But this fixes the problem. Thanks once again!
-- 
Gustavo Narea <xri://=Gustavo>.
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