Today I Learned

Ruby’s |= operator: appends values to the array that don’t already exist.

a = [1]
a |= [2] # a == [1, 2]
a |= [2] # a == [1, 2]

via Facundo Espinosa on Twitter

---

irb accepts an -r option to automatically require gems:

irb -r down

tempfile = Down.download("http://example.com") # look! no require!

via Collin Jilbert on Twitter

---

Ruby on Rails’ missing fetches records that do not have an associated record. For example A Post that does not have any associated Comments:

Post.where.missing(:comments)