Merge pull request #1482 from rstudio/barbara/runapp

Fixes #1358: more informative error message when calling runApp inside of an app's app.R

R/server.R

@@ -462,6 +462,9 @@ serviceApp <- function() {
 
 .shinyServerMinVersion <- '0.3.4'
 
+# Global flag that's TRUE whenever we're inside of the scope of a call to runApp
+.globals$running <- FALSE
+
 #' Run Shiny Application
 #'
 #' Runs a Shiny application. This function normally does not return; interrupt R
@@ -555,6 +558,15 @@ runApp <- function(appDir=getwd(),
     handlerManager$clear()
   }, add = TRUE)
 
+  if (.globals$running) {
+    stop("Can't call `runApp()` from within `runApp()`. If your ,",
+         "application code contains `runApp()`, please remove it.")
+  }
+  .globals$running <- TRUE
+  on.exit({
+    .globals$running <- FALSE
+  }, add = TRUE)
+
   # Enable per-app Shiny options
   oldOptionSet <- .globals$options
   on.exit({