Description Usage Arguments Details Value See Also Examples
runWaterfall
runs its input tasks sequentially, passing each task's
return value to the next task, and returns either a named list
(on error NULL
) or the value of a given callback.
1 | runWaterfall(tasks = list(NULL), cb = NULL)
|
tasks |
List of functions (anonymous and named) required. |
cb |
Anonymous or named function with signature
|
All tasks except the first must have at least one parameter.
If an error is encountered while calling the tasks without a
callback runWaterfall
immediately stops execution and returns
NULL
. If an error is encountered and a callback is defined
runWaterfall
immediately stops execution and calls the callback with
the data
parameter set to NULL
and the error
parameter
set to the encountered error. Thus, the callback will always have only one
non-NULL
argument. Within the callback simply check for an error
with is.null(error)
. If the error
object is not NULL
it has a property $task
indicating the function that failed.
If cb
is NULL
the tasks' return values are returned
in a named list (on error NULL
). If cb
is a function it is
called upon completion of all tasks and gets passed an error value
(default NULL
) as first parameter and a named list of the tasks'
return values (on error NULL
) as second parameter.
runSeries
runRace
runParallel
https://github.com/feross/run-waterfall
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