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9306 :: Compile time detection of experimental compiler feature

• dxb (orginal) [2022-07-15T09:08:37+02:00] view original

  Hi! I have a module that depends on --experimental:views and would like to be able to reliably detect and fail if views are not enabled. I currently do:

  when not compiles(block:
          var x: openArray[int]):
      {.fatal: "--experimental:views is required for this module to work" .}
  Run

  I would prefer to write something like:

  when when compileOption("experimental", "views"):
      {.fatal: "--experimental:views is required for this module to work" .}
  # Or
  when when compileOption("experimental:views"):
      {.fatal: "--experimental:views is required for this module to work" .}
  Run

  but the compiler currently says Error: invalid command line option: '--experimental' (Nim Compiler Version 1.7.1). Any suggestions?

  Thank you.

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• Araq (orginal) [2022-07-15T09:56:45+02:00] view original

  Your module should use {.experimental: "views".}.

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• dxb (orginal) [2022-07-15T10:26:36+02:00] view original

  Thank you @araq. FYI the module did use the experiemental pragma but importing and using the module requires sprinkling other modules with {.experimental: "views".} or enable --experimental:views globally so I switched to detecting if views were enabled globally when importing the module. I think I will stick to what I have now, or turn it into {.error ... } instead of {.fatal ... }, because I prefer providing a clear message to the user upon import: "if you want to use this module you must enable enable views".

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