Types
FutureBase = ref object of RootObj callbacks: CallbackList finished: bool error*: ref Exception ## Stored exception errorStackTrace*: string when not false: stackTrace: seq[StackTraceEntry] ## For debugging purposes only. id: int fromProc: string
- Untyped future. Source Edit
Future[T] = ref object of FutureBase value: T ## Stored value
- Typed future. Source Edit
FutureVar[T] = distinct Future[T]
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FutureError = object of Exception cause*: FutureBase
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Consts
isFutureLoggingEnabled = false
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NimAsyncContinueSuffix = "NimAsyncContinue"
- For internal usage. Do not use. Source Edit
Procs
proc getCallSoonProc(): (proc (cbproc: proc ()) {...}{.gcsafe.}) {...}{.raises: [], tags: [].}
- Get current implementation of callSoon. Source Edit
proc setCallSoonProc(p: (proc (cbproc: proc ()) {...}{.gcsafe.})) {...}{.raises: [], tags: [].}
- Change current implementation of callSoon. This is normally called when dispatcher from asyncdispatcher is initialized. Source Edit
proc callSoon(cbproc: proc ()) {...}{.raises: [Exception], tags: [RootEffect].}
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Call cbproc "soon".
If async dispatcher is running, cbproc will be executed during next dispatcher tick.
If async dispatcher is not running, cbproc will be executed immediately.
Source Edit proc newFuture[T](fromProc: string = "unspecified"): owned(Future[T])
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Creates a new future.
Specifying fromProc, which is a string specifying the name of the proc that this future belongs to, is a good habit as it helps with debugging.
Source Edit proc newFutureVar[T](fromProc = "unspecified"): owned(FutureVar[T])
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Create a new FutureVar. This Future type is ideally suited for situations where you want to avoid unnecessary allocations of Futures.
Specifying fromProc, which is a string specifying the name of the proc that this future belongs to, is a good habit as it helps with debugging.
Source Edit proc clean[T](future: FutureVar[T])
- Resets the finished status of future. Source Edit
proc complete[T](future: Future[T]; val: T)
- Completes future with value val. Source Edit
proc complete(future: Future[void]) {...}{.raises: [FutureError, Exception], tags: [RootEffect].}
- Completes a void future. Source Edit
proc complete[T](future: FutureVar[T])
- Completes a FutureVar. Source Edit
proc complete[T](future: FutureVar[T]; val: T)
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Completes a FutureVar with value val.
Any previously stored value will be overwritten.
Source Edit proc fail[T](future: Future[T]; error: ref Exception)
- Completes future with error. Source Edit
proc clearCallbacks(future: FutureBase) {...}{.raises: [], tags: [].}
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proc addCallback(future: FutureBase; cb: proc () {...}{.closure, gcsafe.}) {...}{. raises: [Exception], tags: [RootEffect].}
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Adds the callbacks proc to be called when the future completes.
If future has already completed then cb will be called immediately.
Source Edit proc addCallback[T](future: Future[T]; cb: proc (future: Future[T]) {...}{.closure, gcsafe.})
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Adds the callbacks proc to be called when the future completes.
If future has already completed then cb will be called immediately.
Source Edit proc callback=(future: FutureBase; cb: proc () {...}{.closure, gcsafe.}) {...}{. raises: [Exception], tags: [RootEffect].}
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Clears the list of callbacks and sets the callback proc to be called when the future completes.
If future has already completed then cb will be called immediately.
It's recommended to use addCallback or then instead.
Source Edit proc callback=[T](future: Future[T]; cb: proc (future: Future[T]) {...}{.closure, gcsafe.})
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Sets the callback proc to be called when the future completes.
If future has already completed then cb will be called immediately.
Source Edit proc `$`(entries: seq[StackTraceEntry]): string {...}{.raises: [ValueError], tags: [].}
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proc read[T](future: Future[T] | FutureVar[T]): T
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Retrieves the value of future. Future must be finished otherwise this function will fail with a ValueError exception.
If the result of the future is an error then that error will be raised.
Source Edit proc readError[T](future: Future[T]): ref Exception
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Retrieves the exception stored in future.
An ValueError exception will be thrown if no exception exists in the specified Future.
Source Edit proc mget[T](future: FutureVar[T]): var T
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Returns a mutable value stored in future.
Unlike read, this function will not raise an exception if the Future has not been finished.
Source Edit proc finished(future: FutureBase | FutureVar): bool
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Determines whether future has completed.
True may indicate an error or a value. Use failed to distinguish.
Source Edit proc failed(future: FutureBase): bool {...}{.raises: [], tags: [].}
- Determines whether future completed with an error. Source Edit
proc asyncCheck[T](future: Future[T])
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Sets a callback on future which raises an exception if the future finished with an error.
This should be used instead of discard to discard void futures, or use waitFor if you need to wait for the future's completion.
Source Edit proc `and`[T, Y](fut1: Future[T]; fut2: Future[Y]): Future[void]
- Returns a future which will complete once both fut1 and fut2 complete. Source Edit
proc `or`[T, Y](fut1: Future[T]; fut2: Future[Y]): Future[void]
- Returns a future which will complete once either fut1 or fut2 complete. Source Edit
proc all[T](futs: varargs[Future[T]]): auto
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Returns a future which will complete once all futures in futs complete. If the argument is empty, the returned future completes immediately.
If the awaited futures are not Future[void], the returned future will hold the values of all awaited futures in a sequence.
If the awaited futures are Future[void], this proc returns Future[void].
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