Works well only as long as this is not a user comment, isn't it?  Yet if it is -- noquote tag should not be a problem...

If you have used the display_eval parameter in your element and then try the display_template above you will be surprised to find the original value presented.

That's because the display_eval param doesn't modify the column value, it makes a new column. Extending the above example:

...
-elements {
  success_bool {
    display_eval {[ad_decode $success_bool t Success "<em>FAIL</em>"]}
    display_template {@foo.success_bool___display;noquote@}
  }
}

Note that the separator is THREE underscore characters. In a similar way if you have constructed an url with the link_url_eval param, you can access that via col_name___link_url

If you want some insight into the upvar magic of Lars and the completeness of listbuilder functionality - take a look at the source for template::list::prepare_for_rendering !

it's debateable which is less clean: setting html code in a database result set versus exploiting the innards of listbuilder

i suspect your way will confuse less people - also saves a hairy uplevel i cooked up to access vars from the page...