From: Vince H&K <vince.hetk@...>
Date: 2007-03-24T05:48:12+09:00
Subject: Re: Knocking Lines Out Of A Multiline String

Brian Candler wrote:
> On Sat, Mar 24, 2007 at 03:39:42AM +0900, Rick DeNatale wrote:
>> On 3/22/07, Robert Klemme <shortcutter@googlemail.com> wrote:
>>
>>> Bullshit: just use select:
>>>
>>>>> "foo\nbar\n".select {|l| /^f/ =~ l}
>>> => ["foo\n"]
>> Or, since he's really trying to exclude lines which include /usr/local/lib:
>>
>> str.reject {|s| Regexp.new("/usr/local/lib").match(s)}
> 
> Why does nobody seem to anchor regexps? I have seen so many documentation
> examples now which suggest that something like
> 
>     raise "Invalid data" unless /[A-Za-z0-9]+/ =~ data
> 
> is a good example of data validation :-(

  I agree that it isn't... However, most of my uses of regexps are to
extract some pieces of data from a bigger text - such as

`identify biniou.jpg` =~ /(\d+)x(\d+)/

  It would be a pain to have to unanchor those... Moreover, it is way
better (in my opinion), to write something like

  raise "Invalid data" if /[^A-Za-z0-9]/ =~ data

  if you really require the full data to be alnum. Or, rather, if you
want to be somehow more flexible (stripping whitespace and other):

raise "Invalid data" unless /([A-Za-z0-9]+)/ =~ data

data = $1 # Cleaning up data...

  Cheers,

      Vincent

-- 
Vincent Fourmond, PhD student (not for long anymore)
http://vincent.fourmond.neuf.fr/