         # File lib/rake.rb, line 690
    690:     def investigation
    691:       result = "------------------------------\n"
    692:       result << "Investigating #{name}\n"
    693:       result << "class: #{self.class}\n"
    694:       result <<  "task needed: #{needed?}\n"
    695:       result <<  "timestamp: #{timestamp}\n"
    696:       result << "pre-requisites: \n"
    697:       prereqs = @prerequisites.collect {|name| application[name]}
    698:       prereqs.sort! {|a,b| a.timestamp <=> b.timestamp}
    699:       prereqs.each do |p|
    700:         result << "--#{p.name} (#{p.timestamp})\n"
    701:       end
    702:       latest_prereq = @prerequisites.collect{|n| application[n].timestamp}.max
    703:       result <<  "latest-prerequisite time: #{latest_prereq}\n"
    704:       result << "................................\n\n"
    705:       return result
    706:     end