added some example usage for the defined test in the doc

diff --git a/doc/02-Twig-for-Template-Designers.markdown b/doc/02-Twig-for-Template-Designers.markdown
index b0b8ef7..abc5038 100644 (file)
--- a/doc/02-Twig-for-Template-Designers.markdown
+++ b/doc/02-Twig-for-Template-Designers.markdown
@@ -1307,7 +1307,18 @@ can use either global constants or class constants:
 ### `defined`
 
 `defined` checks if a variable is defined in the current context. This is very
-useful if you use the `strict_variables` option.
+useful if you use the `strict_variables` option:
+
+    [twig]
+    {# defined works with variable names #}
+    {% if foo is defined %}
+        ...
+    {% endif %}
+
+    {# and attributes on variables names #}
+    {% if foo.bar is defined %}
+        ...
+    {% endif %}
 
 Extensions
 ----------