Mirror of forum.nim-lang.org

6691 :: programmatically create variable in context, using template

• ElAfalw (orginal) [2020-08-18T07:48:03+02:00] view original

  I don't know if a template is the right way to do it, but this is what I'm trying to do:

  
  template doSth(i: int): untyped =
       if i>=1:
            let x = "X"
       if i>=2:
            let y = "Y"
  
  .....
  
  proc someOtherProc() =
        doSth(1)
        echo fmt("x = {x}")
  Run

  Basically, I want to have an "x" variable in someOtherProc.

  How could I do it?

---

• moigagoo (orginal) [2020-08-18T08:12:05+02:00] view original

  You sure can!

  Use inject pragma. Here's an example: https://github.com/moigagoo/norm/blob/develop/src/norm/sqlite.nim#L36

---

• Stefan_Salewski (orginal) [2020-08-18T08:21:30+02:00] view original

  maybe with static, when and inject:

  import strformat
  
  # https://forum.nim-lang.org/t/6616#40996
  #[
  template createVar(name, value) =
    var name {.inject.} = value
  
  createVar(variable, 100)
  ]#
  
  template doSth(i: static[int]): untyped =
       when i >= 1:
            let x {.inject.} = "X"
       when i >= 2:
            let y {.inject.} = "Y"
  
  proc someOtherProc =
        doSth(1)
        echo fmt("x = {x}")
  
  someOtherProc()
  Run

---

• ElAfalw (orginal) [2020-08-18T09:14:58+02:00] view original

  Stefan, thanks!

  Great solution.

---