temp/R6modules1.R

In ari-nz/picnic: Shows you where to go to have a picnic in level 3.1

library(R6)
library(shiny)

Person <- R6::R6Class(
    "Person",
    private = list(
        name = "",
        reactiveDep = NULL,
        reactiveExpr = NULL,
        invalidate = function() {
            private$count <- private$count + 1
            private$reactiveDep(private$count)
            invisible()
        },
        count = 0
    ),
    public = list(
        initialize = function(name=NULL {
            # Until someone calls $reactive(), private$reactiveDep() is a no-op. Need
            # to set it here because if it's set in the definition of private above, it will
            # be locked and can't be changed.
            private$reactiveDep <- function(x) NULL
            private$name <- name
        },
        reactive = function() {
            # Ensure the reactive stuff is initialized.
            if (is.null(private$reactiveExpr)) {
                private$reactiveDep <- reactiveVal(0)
                private$reactiveExpr <- reactive({
                    private$reactiveDep()
                    self
                })
            }
            private$reactiveExpr
        },
        print = function() {
            cat("Person:", private$name)
        },
        changeName = function(newName) {
            private$name <- newName
            private$invalidate()
        },
        getName = function() {
            private$name
        }
    )
)


library(shiny)

ui <- fluidPage(
  actionButton('cn','ChangeName'),
  actionButton('cn','ChangeName'),
  textOutput('name')
)

server <- function(input, output, session) {
    pr <- Person$new()$reactive()

    # The observer accesses the reactive expression
    observeEvent(pr()$getName(), {
        message("Person changed. Name: ", pr()$getName())
    })
    output$name = renderText({
        pr()$getName()
    })

    observeEvent(input$cn, {
        pr()$changeName(paste(sample(letters), collapse=""))
    })

}

shinyApp(ui, server)