Rodent of Unusual Size (Ken Coar): Fun with Ruby exceptions

I'm currently experimenting with a framework in which exceptional conditions should be handled in a uniform manner -- but have more attributes than just a text message. The first thing I managed to come up with (thanks to a suggestion from apeiros on channel irc://irc.freenode.org/#ruby) was this:

 class MyException < RuntimeError
 attr_reader :message
 unless (defined?(RuntimeError_initialize))
 alias_method(:RuntimeError_initialize, :initialize) 
 end
 
 def
    initialize(*args)
 RuntimeError_initialize(@message)
 end
 
 def message=(text)
 @message = text.to_s
 RuntimeError_initialize(@message)
 end
 end
 

apeiros subsequently offered this:

 class MyException < RuntimeError;
 attr_accessor :message
 alias to_s message
 end
 

Which is pretty cool, although it doesn't address all of my needs. Nevertheless, it's another thing to add to the Ruby tricks-bag. The problem is that I don't know what else Ruby's Exception class might do with the text message it stores internally in something other than an instance variable named @message, as shown by this:

 class E < RuntimeError
 def initialize(msg)
 super
 @message =
    'something else'
 end
 end
 
 irb> x = E.new('this thing')
 => #<E: this thing>
 irb> raise x
 E: this thing
 from (irb):35
 from :0
 

So however Exception is storing the message text internally, it apparently is not obviously accessible. And I'm a bit uncertain about substituting a separate mechanism; I'd rather use the one already in place. (Of course, since it's a FLOSS project, I can look at the source to see how it is done.)

Another for the tricks-bag is this one from StackOverflow, which allows you to change all keys of a hash to strings (which might wipe out any folded duplicates like {12=>7, "12"=>8}):

 hash2 = hash1.inject({}) {
    |h, (k, v)| h[k.to_s] = v; h }
 

That was extremely useful since I was working with hashes with symbols for keys -- and JSON doesn't do symbols. (I subsequently reworked things to use string keys, which is less elegant but also less fragile in this scenario.)

Awesome.