debug.rb

# 19/08/10

module Debug
 # Log to a file either a) the value of some variables at the point of
 # invocation or b) a message.
 #
 # The variables are passed inside a block as an array of symbols.
 def Debug.debug(opts={}, &blk)
 msg = []
 if opts.include? :msg
 msg << "#{opts[:msg]}"
 end
 if block_given?
 (yield.map &:to_s).each do |var|
 val = eval var, blk.binding
 msg << "#{var} = #{val}"
 end
 end
 unless msg.empty?
 msg.unshift caller.last.to_s
 log = opts[:log] || "debug.log"
 File.open log, "a" do |log|
 log.write msg.join("\n")
 log.write "\n\n"
 end
 end
 end
end

if __FILE__ == $0
 x = 1
 y = 2
 Debug.debug { [:x, :y] }
 z = 3
 Debug.debug { [:x, :y, :z] }
 Debug.debug msg: "Test"
 Debug.debug
 Debug.debug msg: "Test 2" do
 [:x, :y]
 end
end