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9931 :: How do I declare a proc as returning a (JavaScript) Promise with no return value?

• yalexr (orginal) [2023-02-23T15:42:13+01:00] view original

  Code I have so far : proc addModule*(worklet: AudioWorklet, moduleURL: cstring) : Future {.importjs: "#.addModule(@)".} fails compilation with Error: cannot instantiate 'Future[T]' inside of type definition: 'addModule'; Maybe generic arguments are missing?

  Context : trying to add AudioWorklet support to nim-webaudio

  
  per https://developer.mozilla.org/en-US/docs/Web/API/Worklet/addModule :
  
  Worklet.addModule()
  ...
  Return value
  A Promise that resolves once the module from the given URL has been added. The promise doesn't return any value.
  Run

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• yalexr (orginal) [2023-02-23T15:45:57+01:00] view original

  Okay... so I threw a couple of sticks, one of which seems to work : Future[jsNull] .

  Final declaration proc addModule*(worklet: AudioWorklet, moduleURL: cstring) : Future[jsNull] {.importjs: "#.addModule(@)".}

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• juancarlospaco (orginal) [2023-02-23T16:01:50+01:00] view original

  proc addModule*(worklet: AudioWorklet; moduleURL: cstring) : Future[void] {.importjs: "#.$1(#)".}

  Run

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• yalexr (orginal) [2023-02-23T16:29:02+01:00] view original

  Thanks.

  ps : it's right at the top of the asyncjs docs . I've got some more reading to do, clearly.

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• yalexr (orginal) [2023-02-24T03:07:50+01:00] view original

  @juancarlospaco hi.

  I followed your advice and am still having client code compilation errors.

  Here is what I have so far: Declaration:

  
  proc addModule*(worklet: AudioWorklet, moduleURL: cstring) : Future[void]  {.importjs: "#.$1(#)".}
  Run

  Client code:

  
  proc init(c : AudioContext) : AudioWorkletNode {.async.} =
    discard await c.audioWorklet.addModule("worklets/random-noise-processor.js")
    var n = newAudioWorkletNode(c, "random-noise-processor")
    console.log("1", n)
    return n
  
  var r : AudioWorkletNode = init()
  Run

  Compilation error:

  
  $ nim js test_worklet.nim
  Error: expression 'await addModule(c.audioWorklet, "worklets/random-noise-processor.js")' has no type (or is ambiguous)
  Run

  Then, changing the declaration to this:

  
  proc addModule*(worklet: AudioWorklet, moduleURL: cstring) : Future[jsNull]  {.importjs: "#.$1(#)".}
  Run

  gives this error:

  
  Error: type mismatch: got 'Future[webaudio.AudioWorkletNode]' for 'jsResolve(n)' but expected 'AudioWorkletNode = ref AudioWorkletNodeObj'
  Run

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