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discard """
output: '''5.0 10.0'''
"""
type
MyOpt[T] = object
case has: bool:
of true: val: T
of false: nil
MyVal = object
f: ptr float
proc `=destroy`(x: var MyVal) =
if x.f != nil:
dealloc(x.f)
proc `=sink`(x1: var MyVal, x2: Myval) =
if x1.f != x2.f:
`=destroy`(x1)
x1.f = x2.f
proc `=`(x1: var MyVal, x2: Myval) =
if x1.f != x2.f:
`=destroy`(x1)
x1.f = create(float)
x1.f[] = x2.f[]
proc newVal(x: float): MyVal =
result.f = create(float)
result.f[] = x
template getIt[T, R](self: MyOpt[T], body: untyped, default: R): R =
if self.has:
template it: untyped {.inject.} = self.val
body
else:
default
proc myproc(h: MyOpt[float]) =
let (a, b) = h.getIt((newVal(it), newVal(it * 2)), (newVal(1.0), newVal(1.0)))
echo a.f[], " ", b.f[]
let h = MyOpt[float](has: true, val: 5.0)
myproc(h)
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