From e09745448001f2387ca76c0abf3232aad53df4c5 Mon Sep 17 00:00:00 2001
From: Wilf Wilson <wilf@wilf-wilson.net>
Date: Wed, 17 Feb 2021 11:55:49 +0000
Subject: [PATCH] init: only define GRAPE variables when undefined

---
 init.g | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/init.g b/init.g
index 9dc3d6002..3c1a07d77 100644
--- a/init.g
+++ b/init.g
@@ -27,9 +27,14 @@ fi;
 BindGlobal("DIGRAPHS_IsGrapeLoaded",
            IsPackageMarkedForLoading("grape", "4.8.1"));
 
-if not DIGRAPHS_IsGrapeLoaded then
+# To avoid warnings when GRAPE is not loaded
+if not IsBound(IsGraph) then
   IsGraph := ReturnFalse;
+fi;
+if not IsBound(Vertices) then
   Vertices := IdFunc;
+fi;
+if not IsBound(Adjacency) then
   Adjacency := IdFunc;
 fi;