[Templates] Wrap text in an HTML tag

[Ronald J Kimball]

I'm trying to figure out the best way to wrap part of a string text in 
an HTML tag.  The string will be the result of calling 
Catalyst.localize(), using the quant command for pluralization.

For example:

   [% Catalyst.localize('You have [quant,_1,new message].',
                        new_message_count) %]

Output:

   You have 2 new messages.

Desired:

   You have <span class="highlight">2</span> new messages.

I looked at the replace() filter, but the replace string is a literal 
string, so [% ... | replace('\d+', '<span class="highlight">$1</span>') 
doesn't work.

It seems I'll need to create a custom filter to handle this, but I was 
curious if anyone else had a suggestion.

thanks,
Ronald