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3147 :: Possible ways to check if template is invoked at top level

• cdome (orginal) [2017-09-06T00:01:07+02:00] view original

  Hi,

  I have an exported template which is logically should be called only as a top level statement in other modules. If it is incidentally called inside a proc it breaks thread safety (template changes global var). And this is multithreaded application, nim code is single threaded but wrapping C project is multithreaded.

  I would like to enforce the contract with somehing like:

  when not isTopLevel:
    {.error: "Template should be invoked only from top level"}
  Run

  Any ideas how similar can be achieved?

  Thanks

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• bluenote (orginal) [2017-09-06T08:41:10+02:00] view original

  I had the same question recently: https://forum.nim-lang.org/t/3058

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• Arrrrrrrrr (orginal) [2017-09-06T09:06:24+02:00] view original

  Check out this hack:

  template testScope =
    template ret = return
    when compiles(ret()): echo "Function"
    else:                 echo "Wild West"
  
  proc test = testScope()
  
  test()
  testScope()
  Run

  Not fully tested. Adapted to your needs https://pastebin.com/U8LfDA0Z

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• cdome (orginal) [2017-09-06T11:13:00+02:00] view original

  Thanks. Magnificent hack, seems to work as expected.

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