Add info about using shinyApp and runApp together

R/app.R

@@ -3,11 +3,16 @@
 #' Create a Shiny app object
 #'
 #' These functions create Shiny app objects from either an explicit UI/server
-#' pair (\code{shinyApp}), or by passing the path of a directory that
-#' contains a Shiny app (\code{shinyAppDir}). You generally shouldn't need to
-#' use these functions to create/run applications; they are intended for
-#' interoperability purposes, such as embedding Shiny apps inside a \pkg{knitr}
-#' document.
+#' pair (\code{shinyApp}), or by passing the path of a directory that contains a
+#' Shiny app (\code{shinyAppDir}). You generally shouldn't need to use these
+#' functions to create/run applications; they are intended for interoperability
+#' purposes, such as embedding Shiny apps inside a \pkg{knitr} document.
+#'
+#' Normally when this function is used at the R console, the Shiny app object is
+#' automatically passed to the \code{print()} function, which runs the app. If
+#' this is called in the middle of a function, the value will not be passed to
+#' \code{print()} and the app will not be run. To make the app run, pass the app
+#' object to \code{print()} or \code{\link{runApp}()}.
 #'
 #' @param ui The UI definition of the app (for example, a call to
 #'   \code{fluidPage()} with nested controls)
@@ -22,8 +27,8 @@
 #'   request to determine whether the \code{ui} should be used to handle the
 #'   request. Note that the entire request path must match the regular
 #'   expression in order for the match to be considered successful.
-#' @return An object that represents the app. Printing the object will run the
-#'   app.
+#' @return An object that represents the app. Printing the object or passing it
+#'   to \code{\link{runApp}} will run the app.
 #'
 #' @examples
 #' \donttest{
@@ -38,6 +43,20 @@
 #' )
 #'
 #' shinyAppDir(system.file("examples/01_hello", package="shiny"))
+#'
+#'
+#' # The object can be passed to runApp()
+#' app <- shinyApp(
+#'   ui = fluidPage(
+#'     numericInput("n", "n", 1),
+#'     plotOutput("plot")
+#'   ),
+#'   server = function(input, output) {
+#'     output$plot <- renderPlot( plot(head(cars, input$n)) )
+#'   }
+#' )
+#'
+#' runApp(app)
 #' }
 #'
 #' @export

R/server.R

@@ -535,8 +535,8 @@ serviceApp <- function() {
 
 #' Run Shiny Application
 #'
-#' Runs a Shiny application. This function normally does not return; interrupt
-#' R to stop the application (usually by pressing Ctrl+C or Esc).
+#' Runs a Shiny application. This function normally does not return; interrupt R
+#' to stop the application (usually by pressing Ctrl+C or Esc).
 #'
 #' The host parameter was introduced in Shiny 0.9.0. Its default value of
 #' \code{"127.0.0.1"} means that, contrary to previous versions of Shiny, only
@@ -547,6 +547,9 @@ serviceApp <- function() {
 #' @param appDir The directory of the application. Should contain
 #'   \code{server.R}, plus, either \code{ui.R} or a \code{www} directory that
 #'   contains the file \code{index.html}. Defaults to the working directory.
+#'   Instead of a directory, this could be a list with \code{ui} and
+#'   \code{server} components, or a Shiny app object created by
+#'   \code{\link{shinyApp}}.
 #' @param port The TCP port that the application should listen on. Defaults to
 #'   choosing a random port.
 #' @param launch.browser If true, the system's default web browser will be
@@ -563,8 +566,8 @@ serviceApp <- function() {
 #'   the value \code{"showcase"}, shows application code and metadata from a
 #'   \code{DESCRIPTION} file in the application directory alongside the
 #'   application. If set to \code{"normal"}, displays the application normally.
-#'   Defaults to \code{"auto"}, which displays the application in the mode
-#'   given in its \code{DESCRIPTION} file, if any.
+#'   Defaults to \code{"auto"}, which displays the application in the mode given
+#'   in its \code{DESCRIPTION} file, if any.
 #'
 #' @examples
 #' \dontrun{
@@ -586,6 +589,20 @@ serviceApp <- function() {
 #'     output$plot <- renderPlot({ hist(runif(input$n)) })
 #'   }
 #' ))
+#'
+#'
+#' # Running a Shiny app object
+#' app <- shinyApp(
+#'   ui = bootstrapPage(
+#'     numericInput('n', 'Number of obs', 100),
+#'     plotOutput('plot')
+#'   ),
+#'   server = function(input, output) {
+#'     output$plot <- renderPlot({ hist(runif(input$n)) })
+#'   }
+#' )
+#'
+#' runApp(app)
 #' }
 #' @export
 runApp <- function(appDir=getwd(),