install_gem_from_cache (GemManagement)

    # File lib/merb-core/tasks/gem_management.rb, line 96
      def install_gem_from_cache(gem, options = {})
        version = options.delete(:version)
        Gem.configuration.update_sources = false
        installer = Gem::DependencyInstaller.new(options.merge(:user_install => false))
        exception = nil
        begin
          if gem_file = find_gem_in_cache(gem, version)
            puts "Located #{gem} in gem cache..."
            installer.install gem_file
          else
            raise Gem::InstallError, "Unknown gem #{gem}"
          end
        rescue Gem::InstallError => e
          exception = e
        end
        if installer.installed_gems.empty? && exception
          error "Failed to install gem '#{gem}' (#{e.message})"
        end
        ensure_bin_wrapper_for_installed_gems(installer.installed_gems, options)
        installer.installed_gems.each do |spec|
          success "Successfully installed #{spec.full_name}"
        end
      end