Ticket #919: random_tag.patch

core/template/defaulttags.py

@@ -178 +178 @@
                 return self.nodelist_true.render(context)
         return self.nodelist_false.render(context)
 
+class RandomNode(Node):
+    def __init__(self, nodelist_options):
+        self.nodelist_options = nodelist_options
+
+    def render(self, context):
+        from random import choice
+        return choice(self.nodelist_options).render(context)
+
 class RegroupNode(Node):
     def __init__(self, target_var, expression, var_name):
         self.target_var, self.expression = target_var, expression
@@ -588 +596 @@
     parser.delete_first_token()
     return IfChangedNode(nodelist)
 
+def do_random(parser, token):
+    """
+    Output the contents of a random block.
+
+    The `random` block tag must contain one or more `or` tags, which separate
+    possible choices; a choice in this context is everything between a
+    `random` and `or` tag, between two `or` tags, or between an `or` and an
+    `endrandom` tag.
+
+    Sample usage::
+
+        {% random %}
+        You will see me half the time.
+        {% or %}
+        You will see <em>me</em> the other half.
+        {% endrandom %}
+    """
+    options = NodeList()
+    while True:
+        option = parser.parse(('or', 'endrandom'))
+        token = parser.next_token()
+        options.append(option)
+        if token.contents == 'or':
+            continue
+        parser.delete_first_token()
+        break
+    if len(options) < 2:
+        raise TemplateSyntaxError, "random must have at least two possibilities"
+    return RandomNode(options)
+
 def do_ssi(parser, token):
     """
     Output the contents of a given file into the page.
@@ -770 +808 @@
 register_tag('if', do_if)
 register_tag('ifchanged', do_ifchanged)
 register_tag('regroup', do_regroup)
+register_tag('random', do_random)
 register_tag('ssi', do_ssi)
 register_tag('load', do_load)
 register_tag('now', do_now)