From: William James <w_a_x_man@...>
Date: 2007-08-23T05:01:45+09:00
Subject: Re: Using external text file to do search and replace?

On Aug 22, 6:55 am, Dan George <end...@gmail.com> wrote:
> I recently started to take an interest in Ruby programming and with
> the help of some people and by reading Learn to program by Chris Pine
> I made myself a little program that has come to a halt because I don't
> know if or how I can use an external file where I store the strings I
> want to search and replace in text type files.
>
> This is what I have so far:
>
> txt_files = Dir.glob('**/*.txt').each do |path|
> puts path
> txts = path.to_s
>   file = File.open(txts).readlines.each { |line|
>     if line.match(/PROMOS:/)
>       then line.gsub!(/PROMO1=[A-Za-z0-9]+/, 'PROMO1=some_text')
>     end }
>   file2=File.open(txts, "w")
>   file2.write( file )
> end
>
> What I want is to be able to use an external file where I store the
> values I want to search and replace with "line.gsub!" eg.: "/PROMOn=[A-
> Za-z0-9]+/, 'PROMOn=some_other_text'".
> I will need to use RubyScript2Exe because I'm not sure that on some
> other machines I will have ruby installed and it's easier to just put
> the strings I want to search and replace in an external file that is
> located in the same folder as the script or on a predefined path.
>
> Any ideas, hints, improvements and critiques are highly welcome.

# First line of file is regular expression; second is
# substitution.
temp = IO.readlines( "substitute" ).map{|s| s.chomp }
reg_exp = Regexp.new( temp[0] )
new_text = temp[1]

Dir[ "**/*.txt" ].each{|path|
  p path
  changed = false
  lines = IO.readlines( path ).map{|s|
    if s =~ /PROMOS:/
      old_s = s.dup
      s.gsub!( reg_exp, new_text )
      changed = true   if s != old_s
    end
    s
  }
  # Don't write to file unless there was a change.
  if changed
    File.open( path, "w" ){|f| f.puts lines }
    puts "   ---> changed"
  end
}