When using chameleon, I can replace element from a base template using the concept of slot. Where you define a slot and fill it using another tag. As there is no container element in head, how can one add elements to head ? :
The Layout file
<html>
<head>
<div metal:define-slot="extra_head"></div>
</head>
<body>
...
</body>
</html>
The content template that need to specify extra head.
<html metal:use-macro="load: main.pt">
<div metal:fill-slot="extra_head">
<script type="text/javascript" src="http://example/script.js"></script>
</div>
...
</html>
This gets rendered in :
<html>
<head>
<div metal:fill-slot="extra_head">
<script type="text/javascript" src="http://example/script.js"></script>
</div>
</head>
<body>
...
</body>
</html>
But there's no container tag in head so how can one define a slot to add stuff in the head ?
There's an alternative to using
tal:omit-tag(which I'm finding annoyingly confusing - more than once I spent many minutes trying to figure out why a certain tag does not appear in the output when it's clearly present in the template, only to findtal:omit-tagneatly tucked in the far corner): if you use xml tags withtal:andmetal:namespaces they won't appear in the output:and in the child template:
Note how the template becomes much more readable and self-descriptive and does not contain weird things such as a
<div>inside<head>:)You also can omit
tal:andmetal:prefixes on attributes when using namespaced tags, sobecomes