Difference between || and ||=? [duplicate]

Answer 1

You can expand a ||= 6 as

a || a = 6

So you can see that it use a if a is not nil or false, otherwise it will assign value to a and return that value. This is commonly used for memoization of values.

Update

Thanks to the first comment for pointing out the true expansion of the ||= (or equal) operator. I learned something new and found this interesting post that talks about it. http://dablog.rubypal.com/2008/3/25/a-short-circuit-edge-case