Python short-hand for HTML insertion

In the documentation we find this:

${...} operator

The ${...} notation is short-hand for text insertion. The Python-expression inside the braces is evaluated and the result included in the output (all inserted text is escaped by default):

 <div id="section-${index + 1}">
    ${content}
 </div>

To escape this behavior, prefix the notation with a backslash character: \${...}.

How can I render the content value as HTML instead of text?

To avoid escaping, use the structure: prefix:

<div>${structure: content}</div>

You can also pass an object with a __html__ method:

Note that if an object implements the __html__ method, the result of this method will be inserted as-is (without XML escaping).

Update:

As requested, here is an example of how I think the __html__ method should work. Note that I'm not a Chameleon user and that this code untested :)

class Unescaped(object):
    def __init__(self, value):
        self.value = value

    def __html__(self):
        return self.value

In your template:

<div>${ Unescaped(content) }</div>