From: Jeff Myers <jeff43023@...>
Date: 2010-09-15T05:00:25+09:00
Subject: Re: beginner's q about eval and/or code blocks

Brian Candler wrote:
> Jeff Myers wrote:
>> This ruby program successfully prints all 5-letter words starting with
>> 'j'
>> (in a text file containing all current U.S. English Scrabble words).
>> 
>> fp = File.open('C:\Documents and Settings\User\twl06FromMac.txt')
>> fp.each  do |line|
>>   puts line if line =~ /^j....$/
>> end
>> 
>> I would like to allow the user to enter the regex rather than have it
>> hard-coded as above. I've tried to get eval to work after building a
>> string to pass it. No luck so far.
> 
> Try something like:
> 
> str = $stdin.gets.chomp
> re = Regexp.new(str)
> ...
>   puts line if line =~ re

Excellent! Thanks. Now I'll spend some time digging into the Why of
it all. Apparently the match operator needs one side to be a
regular expression object.
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