obj.nil? vs. obj == nil

ruby null comparison
Danish Khan picture Danish Khan · Dec 29, 2009 · Viewed 16.6k times · Source

Is it better to use obj.nil? or obj == nil and what are the benefits of both?

Answer

OscarRyz picture OscarRyz · Dec 29, 2009

Is it better to use obj.nil? or obj == nil

It is exactly the same. It has the exact same observable effects from the outside ( pfff ) *

and what are the benefits of both.

If you like micro optimizations all the objects will return false to the .nil? message except for the object nil itself, while the object using the == message will perform a tiny micro comparison with the other object to determine if it is the same object.

* See comments.

Related questions

Best ruby idiom for "nil or zero"

I am looking for a concise way to check a value to see if it is nil or zero. Currently I am doing something like: if (!val || val == 0) # Is nil or zero end But this seems very clumsy.

Read More
Is there a Ruby, or Ruby-ism for not_nil? opposite of nil? method?

I am not experienced in Ruby, so my code feels "ugly" and not idiomatic: def logged_in? !user.nil? end I'd rather have something like def logged_in? user.not_nil? end But cannot find such a method that opposites …

Read More
Not assigning nil values to a hash

Is there a short hand or best practice for assigning things to a hash when they are nil in ruby? For example, my problem is that I am using another hash to build this and if something in it is …

Read More