tiny Rack middleware to have Yell::Logger log exceptions nicely.

yell_exceptions.rb

# tom@jitter.eu https://gist.github.com/gretel/388f14f1de38174ea790 09/2014 MIT License
# Rack middleware to Yell (https://github.com/rudionrails/yell) exceptions

# config.ru:
#   require 'yell_exceptions'
#   use Rack::YellExceptions

require 'yell'

module Rack
  class YellExceptions
    attr_accessor :str

    def initialize(app, log = nil, str = nil)
      @app = app
      log ||= yeller
      fail unless log.kind_of? Yell::Logger
      @logger = log
      str ||= "%s\n%s\n%s"
      @str = str
    end

    def call(env)
      begin
        response = @app.call(env)
      rescue Object => e
        except(e, env)
        raise
      end
      response
    end

    private

    def except(e, env = nil)
      @logger.fatal(sprintf(@str, e, e.backtrace.join("\n"), env.to_a[0].to_s)) # todo: test
    end

    def yeller
      return Object.logger if Object.logger.kind_of? Yell::Logger
      Yell.new :stdout, name: self.class
    end
  end
end