defer_speed.nim

import times

type AThing = ref object
  i: int

iterator items(a:AThing): int =

  when defined(dodefer):
    defer:
      a.i = 11
  else:
    a.i = 11

  for i in 0..a.i:
    yield i

proc speed(n:int): int =
  var j:int
  var a = AThing(i:10)
  var l = 0
  for k in 0..<n:
    j = 0
    for i in a:
      j += 1
      if i > 5: break
      l += 1
    doAssert j > 0
  doAssert a.i == 11
  echo l
  return j

import times

when defined(dodefer):
  echo "using defer"
else:
  echo "no defer compile with -d:dodefer to check speed"

const N = 50000000
var t = cpuTime()
echo speed(N)
echo cpuTime() - t