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#
#
# Nim's Runtime Library
# (c) Copyright 2022 Nim contributors
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## `outParamsAt` macro for easy writing code that works with both 2.0 and 1.x.
import std/macros
macro outParamsAt*(positions: static openArray[int]; n: untyped): untyped =
## Use this macro to annotate `out` parameters in a portable way.
runnableExamples:
proc p(x: var int) {.outParamsAt: [1].} =
discard "x is really an 'out int' if the Nim compiler supports 'out' parameters"
result = n
when defined(nimHasOutParams):
var p = n.params
for po in positions:
p[po][^2].expectKind nnkVarTy
p[po][^2] = newTree(nnkOutTy, p[po][^2][0])
when isMainModule:
{.experimental: "strictDefs".}
proc main(x: var int) {.outParamsAt: [1].} =
x = 3
proc us =
var x: int
main x
echo x
us()
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