From: Ronald Fischer <ronald.fischer@...>
Date: 2007-06-28T22:15:43+09:00
Subject: Processing rc  file - critical comment asked

I have already a solution for my problem, but I would be glad if some
kind 
soul could have a look on it and give suggestion for improvement...

Problem: My application can be controled by a kind of "rc file",
specifying
various options. The options are defined using the Ruby syntax for
defining
constants. For example:

  # Example rc file
  TIMEOUT=130
  LOGFILE=ENV[HOME]+"/tmp/appl.log"

There are many possible options, but of course not all of them need to
be specified.

My solution is basically to evaluate the option file and access the
constants. I am aware that this imposes a pretty high security risk,
since *any* Ruby code could be put into the rc file, but for my 
application I can accept it - security is not a big issue in this 
particular case.

An option is "set" by calling a certain function in my application.

Here is my code:

# Evaluate RC file in the context of a module. The name of the
# rc file is on variable rcfile.
eval("module Rc\n"+File.read(rcfile)+"\nend")

# Now set the options according to the RC file
Scheduler.setTimeout(Rc::TIMEOUT) if Rc.const_defined?('TIMEOUT');
Logger.setLogFile(Rc::LOGFILE) if Rc.const_defined?('LOGFILE');
... and so on

This works fine, but I don't like it much. It is a lot of typing for
each option, and it is easy to make a typing error:

# Ooops, typo (REMOTEHOST vs. REMOTE_HOST)
SshConnect.setHost(Rc::REMOTEHOST) if Rc.const_defined?('REMOTE_HOST')

Any idea of how I could do it better?

Ronald
-- 
Ronald Fischer <ronald.fischer@venyon.com>
Phone: +49-89-452133-162