class Gem::Commands::OutdatedCommand

def execute
  Gem::Specification.outdated.sort.each do |name|
    local   = Gem::Specification.find_all_by_name(name).max
    dep     = Gem::Dependency.new local.name, ">= #{local.version}"
    remotes, _ = Gem::SpecFetcher.fetcher.spec_for_dependency dep
    next if remotes.empty?
    remotes.sort! { |a,b| a[0].version <=> b[0].version }
    highest = remotes.last.first
    say "#{local.name} (#{local.version} < #{highest.version})"
  end
end

def initialize
  super 'outdated', 'Display all gems that need updates'
  add_local_remote_options
  add_platform_option
end