Safely loading a hash in Ruby

Question

I want to load a data structure into a Ruby script which maps a string to a triple which contains some combination of regular expressions, scripts and atoms. The file that it loads from needs to be human writeable.

Currently I'm writing the file to contain a Ruby hash, loading that as a string and calling eval. Ie.

Data file

{ "key1" => [ /pattern/, "text", "text" ],
  "key2" => [ "text2", :nil, "text3" ],
  "key3" => [ "text4", /pattern2/, /pattern3/ ] }

Script

def get_mapping
  f = File.new path
  return eval(f.read())
end

This is fine and works, but feels (i) like a bit of a hack, (ii) unsafe. So I'm curious to know: is there a better way of doing this?

It's almost JSON but I don't think that can handle atoms or regular expressions easily. The file format can be changed as look as it remains reasonably human read/writeable.

Answer 1

You should really be using YAML for this sort of stuff, your code is really risky.

YAML supports regexps and is fairly extensible.

Answer 2

Hashes and Arrays can be marshalled. This might be helpful if you want to store data from your program in a file. If you are interested in giving user a chance to provide data in external file you can take a look at YAML.