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These functions were created before getDefaultReactiveDomain() existed, so the only way to get ahold of the current session was if the caller explicitly passed it. This is slightly backwards incompatible, in that existing calls to invalidateLater() that don't pass a session argument will behave slightly differently (bound to the current session instead of to no session), but those calls would have triggered a warning for all but the very earliest versions of Shiny.
68 lines
2.1 KiB
R
68 lines
2.1 KiB
R
% Generated by roxygen2 (4.1.1): do not edit by hand
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% Please edit documentation in R/reactives.R
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\name{reactiveTimer}
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\alias{reactiveTimer}
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\title{Timer}
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\usage{
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reactiveTimer(intervalMs = 1000, session = getDefaultReactiveDomain())
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}
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\arguments{
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\item{intervalMs}{How often to fire, in milliseconds}
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\item{session}{A session object. This is needed to cancel any scheduled
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invalidations after a user has ended the session. If \code{NULL}, then
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this invalidation will not be tied to any session, and so it will still
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occur.}
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}
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\value{
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A no-parameter function that can be called from a reactive context,
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in order to cause that context to be invalidated the next time the timer
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interval elapses. Calling the returned function also happens to yield the
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current time (as in \code{\link{Sys.time}}).
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}
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\description{
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Creates a reactive timer with the given interval. A reactive timer is like a
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reactive value, except reactive values are triggered when they are set, while
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reactive timers are triggered simply by the passage of time.
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}
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\details{
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\link[=reactive]{Reactive expressions} and observers that want to be
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invalidated by the timer need to call the timer function that
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\code{reactiveTimer} returns, even if the current time value is not actually
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needed.
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See \code{\link{invalidateLater}} as a safer and simpler alternative.
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}
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\examples{
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\dontrun{
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shinyServer(function(input, output, session) {
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# Anything that calls autoInvalidate will automatically invalidate
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# every 2 seconds.
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autoInvalidate <- reactiveTimer(2000)
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observe({
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# Invalidate and re-execute this reactive expression every time the
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# timer fires.
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autoInvalidate()
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# Do something each time this is invalidated.
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# The isolate() makes this observer _not_ get invalidated and re-executed
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# when input$n changes.
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print(paste("The value of input$n is", isolate(input$n)))
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})
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# Generate a new histogram each time the timer fires, but not when
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# input$n changes.
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output$plot <- renderPlot({
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autoInvalidate()
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hist(isolate(input$n))
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})
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})
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}
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}
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\seealso{
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\code{\link{invalidateLater}}
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}
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