[newbie] string pattern instead of regexp

ruby-talk
1

I’m doing some experiment using the “rubyguide” giving this script :

#!/usr/bin/ruby

regex.rb

Requires an ANSI terminal!

st = “\033[7m”
en = “\033[m”

while TRUE
print "str> "
STDOUT.flush
str = gets
break if not str
str.chop!
print "pat> "
STDOUT.flush
re = gets
break if not re
re.chop!
str.gsub! re, “#{st}\&#{en}”
print str, “\n”
end

print “\n”

when trying it i get the following warning :

pp:~/Applications/Ruby/Tutorial> ruby regex.rb

foobar
^fo+
regex.rb:19: warning: string pattern instead of regexp; metacharacters
no longer effective
foobar
abc012dbcd555
\d
regex.rb:19: warning: string pattern instead of regexp; metacharacters
no longer effective
abc012dbcd555

does that means my term isn’t an ANSI one or the syntax as changed ?
tuto is mostly from v 1.4 and i’m using v1.8 under MacOS X.2.6

···

–
Yvon

2

regex.rb:19: warning: string pattern instead of regexp; metacharacters
no longer effective

Well, the message say that ruby will not interpret metacharacter (this is
a change in 1.8). Create a Regexp object from the String

  re.chop!

     re = Regexp.new(re.chomp)

  str.gsub! re, "#{st}\\&#{en}"
  print str, "\n"
end

Guy Decoux

3

As far as I know, this warning was added some times ago (in 1.7.x ?)
after a slight semantic change, to make sure users would know about it.
Before, a single character string would be treated as a string, and all
others would be converted to regexp.

The behavior is now that strings will be strings, and regexp will be
regexp. I expected this warning to go away in 1.8 but looking at ruby
code (string.c) it looks like it will go away in 1.8.1.

So in short, your gsub won’t work like you expect here because you pass
it a string when you actually want a regexp.

Replace:

str.gsub! re, “#{st}\&#{en}”

by:

str.gsub! Regexp.compile(re), “#{st}\&#{en}”

or

str.gsub! /#{re}/, “#{st}\&#{en}”

···

Yvon Thoraval <yvon.thoravallist@-SUPPRIMEZ-free.fr.invalid> wrote:

does that means my term isn’t an ANSI one or the syntax as changed ?
tuto is mostly from v 1.4 and i’m using v1.8 under MacOS X.2.6

–
Luc Heinrich - lucsky@mac.com

4

it’s what i’ve suspected, works fine now, tanxs !

···

Luc Heinrich lucsky@mac.com wrote:

does that means my term isn’t an ANSI one or the syntax as changed ?
tuto is mostly from v 1.4 and i’m using v1.8 under MacOS X.2.6

As far as I know, […]
So in short, your gsub won’t work like you expect here because you pass
it a string when you actually want a regexp.

Replace:

str.gsub! re, “#{st}\&#{en}”

by: […]

str.gsub! /#{re}/, “#{st}\&#{en}”

–
Yvon