Micro-benchmark to test `||=` and `[]=` vs. explicit initialize xor `[]=`

benchmark.rb

#!/usr/bin/env ruby

require 'benchmark'

keys = ('aa'..'zz').map(&:to_sym)

Benchmark.bm do |b|
  n = 10_000

  b.report('lazy initialize') do
    n.times do
      hash = nil

      keys.each do |key|
        hash ||= {}
        hash[key] = 1
      end
    end
  end

  b.report('explicit initialize') do
    n.times do
      hash = nil

      keys.each do |key|
        if hash
          hash[key] = 1
        else
          hash = {key => 1}
        end
      end
    end
  end
end

Agree to @sanG-github Nope, that would then only set the very first key.

Alternative:

else # !hash
  hash = {}
  hash[key] = 1
end

In my case, doesnt have much effect on the benchmark results, though.
Quicker implementation in my short tests is

b.report('explicit initialize, always assign') do
    n.times do
      hash = nil

      keys.each do |key|
        if !hash
          hash = {}
        end

        hash[key] = 1
      end
    end
 end