Ruby style poll

gistfile1.rb

#Do you prefer this?

      merchant["thing"] = important_stuff.map { |important_thing| important_thing["units"] }.inject(&:+)

#Or this?

      important_stuff.each { |important_thing| merchant["thing"] += important_thing["units"] }


#Why? Is it completely objective? Or are ruby's idioms/social mores/conventions the deciding factor?

Forgot a :c => 0 in there

# easy to see we're doing x = y
hash = {}
hash[:a] = [1, 2, 3, 4].map { |x| x + 1 }.inject(&:+)
hash[:b] = "asdf123"
hash[:c] = [2, 9, 8].map { |x| x * 2 }.inject(&:+)

# have to scan around to see what's going on
hash = { :a => 0, :c => 0 }
[1, 2, 3, 4].each { |x| hash[:a] += (x + 1) }
hash[:b] = "asdf123"
[2, 9, 8].each { |x| hash[:c] += x * 2 }.inject(&:+)

I still like the .sum solution, but @fredericksgary's point is what makes me like #1 a little more than just an inject.

Is there something that makes a pure inject clearer than solution #1? Objectively, it's one loop vs two. You could argue that one loop is executing fewer instructions, but I think two simple loops is clearer than one (slightly) more complex one.