From: Mike Stok <mike@...>
Date: 2006-08-13T14:12:57+09:00
Subject: Re: perl tr and ruby String#tr


On 12-Aug-06, at 11:44 PM, snacktime wrote:

>> Can you give me a hint as to what doesn't work?  For a simple upper
>> case subset of your code (using double quotes) I see
>
> I'm implementing string parity functions using perl's String::Parity
> as the base to work from.   I'm assuming that the ruby code is working
> as it was designed to, but I want to find out what I need to do to
> make it work like the perl example.  I just posted a shorter, easier
> to test version.  The perl version outputs a string correctly set to
> even parity.  The ruby code doesn't.     I've tried quotes, no quotes,
> double quotes, eval, beating my head in the wall, all of that.  It's
> something else I am missing.
>
> Chris

I think it's due to multiple interpolations - first in double quotish  
context and then as a pattern for tr, where \ and - are the only real  
metacharacters.

Looks like you need to do something like use \\\55 in place of \55 (a  
- character) and \\\134 in place of \134 (a \ character)

Ick.

Program and output below

#!/usr/bin/env ruby

str = "()*+,-./09AZ[_]abcpqrstuvwxyz\376"
p str
str.tr!("\0-\377","\0\201\202\3\204\5\6\207\210\11\12\213\14\215\216 
\17\220\21\22\223\24\225\226\27\30\231\232\33\234\35\36\237\240\41\42 
\243\44\245\246\47\50\251\252\53\254\\\55\56\2570\261\2623\26456\267 
\2709\72\273\74\275\276\77\300AB\303D\305\306GH\311\312K\314MN\317P 
\321\322S\324UV\327\330YZ\333\\\134\335\336_\140\341\342c\344ef\347 
\350ij\353l\355\356o\360qr\363t\365\366wx\371\372\173\374\175\176\377 
\0\201\202\3\204\5\6\207\210\11\12\213\14\215\216\17\220\21\22\223\24 
\225\226\27\30\231\232\33\234\35\36\237\240\41\42\243\44\245\246\47\50 
\251\252\53\254\\\55\56\2570\261\2623\26456\267\2709\72\273\74\275\276 
\77\300AB\303D\305\306GH\311\312K\314MN\317P\321\322S\324UV\327\330YZ 
\333\\\134\335\336_\140\341\342c\344ef\347\350ij\353l\355\356o\360qr 
\363t\365\366wx\371\372\173\374\175\176\377")
p str

output:

"()*+,-./09AZ[_]abcpqrstuvwxyz\376"
"(\251\252+\254-.\25709AZ\333_\335\341\342c\360qr\363t\365\366wx\371 
\372~"

Hope this helps,

Mike

-- 

Mike Stok <mike@stok.ca>
http://www.stok.ca/~mike/

The "`Stok' disclaimers" apply.