R Shiny: Use reactiveValues() with data.table assign-by-reference

Question

I have a shiny app in which more than one reactive component uses the same result from a function that is slow to calculate. To avoid calculating the slow function more tha

Answer 1

say you have defined a reactive variable table_updated so you can increment it by one each time the slow function is done. Other values/plots will only need to observe table_updated.

Actually the actionButton(see description section) does the same thing, every time it gets clicked, its value is incremented by 1.

values <- reactiveValues(table_updated = 0)

slow.func = function(my.dt, x) {
  # do stuff
  values$table_updated <- values$table_updated + 1
}

output$result2 = renderText({
  values$table_updated
  paste('Final value =', values$dt[100,]$v2)
})