Mirror of forum.nim-lang.org

3416 :: Possible to have a template inside of another template?

• jackmott (orginal) [2017-12-12T16:56:52+01:00] view original

  I have a template like so:

  template SIMD(width:untyped,body:untyped) =

  and I'd like to make a template like this;

  template simdFor[T](a:openarray[T], body:untyped) =
      for i in countup(0,a.len,width): #etc
  Run

  where the second template depends on the width variable from the first template existing. Is something like this possible? I tried this directly and get strange errors, which I suspect may just mean you can't have templates in templates.

---

• Araq (orginal) [2017-12-12T16:58:14+01:00] view original

  templates in templates work but your for loop is not run at compile-time. I think you need to move that logic into a macro.

---

• jackmott (orginal) [2017-12-12T17:01:54+01:00] view original

  I don't want the for loop to run at compile time, so that is ok.

  I was able to print out the template expansion at compile time and it looks like when I added the inner template, the body gets a single quote character appended to it.

  edit: ok, I tracked down the issue.

  template1 used a parameter named body, innertemplate also used a parameter named body. This seems to have caused the problem.

---