is.fmError: Check if object is of fmError class

In Boehringer-Ingelheim/FutureManager: Background Operations in Shiny

Description

This is useful when using helper functions in the long running function.

Usage

is.fmError(x)

Arguments

x	object to test

Value

logical

Examples

if (interactive()) {
  library(shiny)
  plan(fmParallelStrategy())
  
  helper <- function(n){
    if (n < 0) return(fmError("n must be >= 0"))
    log(n)
  }
  longFun <- function(task, n){
    x <- helper(n)
    if (is.fmError(x)) return(x)
    x^2
  }
  
  shinyApp(
    ui = basicPage(
      uiOutput("button"), 
      numericInput("n", "n", -3, -5, 5), 
      textOutput("result")
    ),
    server = function(input, output, session){
      fm <- FutureManager$new(input, session)
      output$button <- renderUI(fmRunButton("run", fm))
      Res <- reactiveVal()
      Args <- reactive(list(n = input$n))
      fm$registerRunObserver("run", NULL, Res, longFun, Args, progress = FALSE)
      output$result <- renderText({
        res <- Res()
        fmValidate(res)
        fmGetValue(res)
      })
    }
  )
}

Boehringer-Ingelheim/FutureManager documentation built on June 16, 2021, 6:23 p.m.