gargoyle example using init, trigger and watch

gargoyle_minimal_example.R

library(shiny)
library(gargoyle)

ui <- function(){
  tagList(
    actionButton("go", "Show me"),
    h4('Output of pass_around$data'),
    tableOutput("table")
  )
}

server <- function(input, output, session){
  
  # Initiating the flags
  init("airquality", "iris", "renderiris")
  
  # Creating a new env to store values, instead of
  # a reactive structure
  pass_around <- new.env()
  
  observeEvent(input$go , {
    pass_around$data <- mtcars
    # Triggering the flag
    trigger("airquality")
  })
  
  on("airquality", {
    # Triggering the flag
    pass_around$data <- airquality
    trigger("iris")
  })
  
  on("iris", {
    # Triggering the flag
    pass_around$data <- iris
    trigger("renderiris")
  })
  
  output$table <- renderTable({
    # This part will only render when the renderiris
    # flag is triggered
    watch("renderiris")
    head(pass_around$data) 
  })
  
}

shinyApp(ui, server)