# bad
def flagged?
@flagged ||= fetch_value_from_server # it fetches always when @flagged = false or nil
end
# better
def flagged?
return @flagged if defined?(@flagged)
@flagged = fetch_value_from_server
end
http://www.jetthoughts.com/blog/tech/2015/08/17/how-to-memoize-false-and-nil-values.html