From: Robert Klemme <shortcutter@...>
Date: 2008-12-11T17:17:00+09:00
Subject: Re: problems in String type argument for Regular Expression

2008/12/11 Jun Young Kim <jykim@altibase.com>:
> I've one program to replace text's contents.
>
> def replace (aPatten, aReplace)
>
>        # I need some logic to translate string to patten
>
>        contents = File.read("data")
>        contents.gsub!(aPatten, aReplace)
>        File.open("result", "w") do |file|
>                file << contents
>        end
> end
>
>
> Another class give an aPatten argument as a "/[aeiou]/" and aReplace as a
> "*". Both of them are String type.
>
> And I know I can get a normal result when I put in /[aeiou]/ instead of
> "/[aeiou]/".
>
> Any ideas on how to do I convert string to patten?

How about looking at the documentation?

http://www.ruby-doc.org/core/classes/Regexp.html

Btw, I rather tend to make it a requirement that the argument has the
appropriate type.  Since #gsub is capable of working with String and
Regexp as pattern, I would not change your method's implementation but
the code invoking it.

Taking this one step further: I would choose a different abstraction:

def transform from_file, to_file
  repl = yield(File.read(from_file)) and
  File.open(to_file, "w") do |io|
    io.write(repl)
  end
end

Then you can do

transform "data", "result" do |content|
  content.gsub! /[aeiou]/, "*"
  content
end

Cheers

robert

-- 
remember.guy do |as, often| as.you_can - without end