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5993 :: Templates and imports

• c0ntribut0r (orginal) [2020-02-26T23:27:44+01:00] view original

  Hello folks,

  Does anyone know why templates don't "auto-import" symbols defined in their residence file? :( Minimal example:

  # test.nim
  import strutils
  
  template test_template*() =
    echo (1.0/3.0).formatFloat(precision=3)
  
  proc test_proc*() =
    echo (1.0/3.0).formatFloat(precision=3)
  Run

  # other.nim
  import test
  
  test_proc()  # ok
  test_template()  # fail:
  # /tmp/other.nim(4, 14) template/generic instantiation of `test_template` from here
  # /tmp/test.nim(5, 17) Error: attempting to call undeclared routine: 'formatFloat'
  Run

  Is it a new feature or a bug? I think it worked in a different way some time ago.

  
  Nim Compiler Version 1.1.1 [Linux: amd64]
  Compiled at 2020-02-25
  git hash: db540a0223480134598fb4806c55510cdef36bf1
  Run

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• solo989 (orginal) [2020-02-27T00:06:00+01:00] view original

  It works if you define it like this:

  # test.nim
  import strutils
  
  template test_template*() =
    echo formatFloat(1.0/3.0,precision=3)
    #echo (1.0/3.0).formatFloat(precision=3)
  
  proc test_proc*() =
    echo (1.0/3.0).formatFloat(precision=3)
  Run

  Still seems like a bug.

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• treeform (orginal) [2020-02-27T00:06:36+01:00] view original

  Hmm, I think it always worked like this. Template just substitute code. If the code where you have template can't access some thing... then it's an error.

  It also is an error if template calls a private proc:

  proc b() = # private b
    echo "hi"
  
  tempalte a*() = # public a
    b()
  Run

  Calling a() in another module will not work because b() is private.

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• doofenstein (orginal) [2020-02-27T00:22:07+01:00] view original

  it works if you change the template:

  template test_template*() =
    echo formatFloat((1.0/3.0), precision=3)
  Run

  See https://nim-lang.org/docs/manual.html#templates-limitations-of-the-method-call-syntax and https://nim-lang.org/docs/manual.html#generics-symbol-lookup-in-generics

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• solo989 (orginal) [2020-02-27T00:24:18+01:00] view original

  Your code works @treeform as long as you fix the typo in tempalte

  proc b() =
    echo "hi"
  
  template a*() =
    b()
  Run

  Inside template a, b is a sym,closedSymChoice or openSymChoice so it works regardless of whether or not b is private or not.

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• DeletedUser (orginal) [2020-02-27T02:03:50+01:00] view original

  use bind

  import strutils
  
  template test_template*() =
    bind formatFloat
    echo (1.0/3.0).formatFloat(precision=3)
  
  proc test_proc*() =
    echo (1.0/3.0).formatFloat(precision=3)
  Run

  https://nim-lang.org/docs/manual.html#generics-bind-statement

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• juancarlospaco (orginal) [2020-02-27T04:16:16+01:00] view original

  https://github.com/nim-lang/Nim/wiki/Nim-for-Python-Programmers#Templates

  Far from perfect, but better than nothing, Templates explanation.

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