From: dave.burt@...
Date: 2005-10-28T11:07:04+09:00
Subject: Re: "Reflecting" on my self.n00b

You can save yourself some RSI by using attr_accessor.

class ServiceProfile
  attr_accessor :username, :url, :password, :owner, :certificate
  def load_certificate()
    @certificate.read
  end
  def call
    yield self
  end
  def each_attribute(&block)
    (methods - Object.instance_methods).each &block
  end
end
class MyService < ServiceProfile
  attr_accessor :extra
end

svc_profile = MyService.new
svc_profile.each_attribute do |meth|
  print "Enter #{meth}: "
  svc_profile.send(meth, gets.chomp)
end
svc_profile.each_attribute {|meth| puts svc_profile.send(meth) }

If you want to use validation, too, you can easily write a method like
attr_accessor. See Dwemthy's Array for how.
http://poignantguide.net/dwemthy/

A type-checking attr_accessor-ish method might look something like
this:

def ServiceProfile.typed_attr(hash)
  attr_reader *hash.keys
  hash.each_pair do |attr, klass|
    define_method("#{attr}=") do |value|
      raise TypeError, "not a #{klass}: #{value.inspect}" unless
value.kind_of?(klass)
      instance_variable_set "@#{attr}", value
    end
  end
end

Cheers,
Dave