Fail with new igraph version

Author: krlmlr

R/versions.R

@@ -97,14 +97,20 @@ upgrade_graph <- function(graph) {
 ## Check that the version is the latest
 
 warn_version <- function(graph) {
-  if (graph_version() != graph_version(graph)) {
+  their_version <- graph_version(graph)
+
+  if (pkg_graph_version == their_version) {
+    return(FALSE)
+  }
+
+  if (pkg_graph_version > their_version) {
     message(
       "This graph was created by an old(er) igraph version.\n",
       "  Call upgrade_graph() on it to use with the current igraph version\n",
       "  For now we convert it on the fly..."
     )
-    TRUE
-  } else {
-    FALSE
+    return(TRUE)
   }
+
+  stop("This graph was created by a new(er) igraph version. Please install the latest version of igraph and try again.")
 }