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[REBOL] Re: parse question

From: gjones05:mail:orion at: 27-Jun-2001 5:52

Hi, Graham, Brett, Joel, I don't seem to be able to muster the skills to articulate an argument one way or the other, which is just as well, because you would present a formidable opponents. :-) So, when I don't feel up to a good argument, I simply present a different way of thinking about the "problems" at hand and will leave to each individual user whether the approach is useful.
>From "Graham Chiu"
> parse {a="b"} [ thru {a="} copy test to {"} ]
... and ...
> parse {a=""} [ thru {a="} copy test to {"} ]
Pardon me if I am not using the terminology correctly, but to most simply coerce the result to a specific type, here was how I saw the problem: parse to-block {a="b"} ['a= set t string! to end] ; == true t ; == "b" parse to-block {a=""} ['a= set t string! to end] ; == true t ; == "" From: "Joel Neely" ...
> Any time you wish to build a new string from the parsed > substrings, or print their content, you have a problem with > NONE! instead of an empty string. For example, given:
... I understand that your example was presented as a piece of an argument meant to demonstrate a concrete side effect of the behavior in question. Here was how I saw the problem: addr1: "John Doe/123 Lonely St/Suite 16/Los Angeles/CA/90210" addr2: "Joe Doaks/321 Hilltop Ln//Green Mtn/MA/02187" print-address-label: function [ s [string!] ][ addr-name addr-line1 addr-line2 addr-city addr-state addr-ZIP ][ foreach [addr-name addr-line1 addr-line2 addr-city addr-state addr-zip] parse/all s "/" [ print [ addr-name newline addr-line1 newline addr-line2 newline addr-city addr-state addr-ZIP newline ] ] ]
>> print-address-label addr1
John Doe 123 Lonely St Suite 16 Los Angeles CA 90210
>> print-address-label addr2
Joe Doaks 321 Hilltop Ln Green Mtn MA 02187 I guess a "blank" line is better than a "none" line for this trivial ("no-additional-logic-added") example. Remember, Joel, (et al,) "It's turtles all the way down!" (I had to look that one up, BTW. If I had ever heard it before, I had certainly forgotten it. :-) --Scott Jones