ruby - 在 Ruby 中，是否有必要内存一个返回常量值/对象的方法？

Question

给定以下方法:

def some_hash
  {
    :one => 1,
    :two => 2,
  }
end

内存哈希是否有任何性能优势？

def some_hash
  @some_hash ||= {
    :one => 1,
    :two => 2,
  }
end

Answer 1

似乎内存变体快了大约 7.5 倍:

def hash1
  {
    :one => 1,
    :two => 2,
  }
end

def hash2
  @some_hash ||= {
    :one => 1,
    :two => 2,
  }
end


require 'benchmark'

Benchmark.bmbm do |b|
  b.report do
    1_000_000.times{ hash1 }
  end
end

Benchmark.bmbm do |b|
  b.report do
    1_000_000.times{ hash2 }
  end
end

Rehearsal ------------------------------------
   1.470000   0.030000   1.500000 (  1.499750)
--------------------------- total: 1.500000sec

       user     system      total        real
   1.570000   0.030000   1.600000 (  1.739230)
Rehearsal ------------------------------------
   0.210000   0.000000   0.210000 (  0.231601)
--------------------------- total: 0.210000sec

       user     system      total        real
   0.210000   0.010000   0.220000 (  0.234898)