From 8ddcdfd33edf44303c54f2fb79f3e54920222643 Mon Sep 17 00:00:00 2001
From: Jeremy Siek <jeremy.siek@gmail.com>
Date: Thu, 6 Dec 2001 16:20:33 +0000
Subject: [PATCH] added more warnings and examples

[SVN r11956]
---
 include/boost/graph/iteration_macros.hpp | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/boost/graph/iteration_macros.hpp b/include/boost/graph/iteration_macros.hpp
index 05a2813f..8ee138e3 100644
--- a/include/boost/graph/iteration_macros.hpp
+++ b/include/boost/graph/iteration_macros.hpp
@@ -28,6 +28,27 @@
     BGL_FORALL_VERTICES(v, g, graph_t) {
         bar(v);
     }
+
+  Instead write this:
+
+  if (sky_is_blue) {
+    BGL_FORALL_VERTICES(v, g, graph_t) {
+        bar(v);
+    }
+  }
+
+  Another example of what NOT to write:
+
+  BGL_FORALL_VERTICES(u, g, graph_t)
+    BGL_FORALL_VERTICES(u, v, g, graph_t)
+      foo(u, v);
+
+  Instead write this
+
+  BGL_FORALL_VERTICES(u, g, graph_t) {
+    BGL_FORALL_VERTICES(u, v, g, graph_t)
+      foo(u, v);
+  }
   
   It is OK to use single statements after the macro: