Nobody got any bright ideas? I'm really stuck here!
attribute_view_gui seems to only want an object, not a string, so there doesn't seem to be any way to pipe the value to the 'break' function and then have it be displayed.
1) Showing it using the attribute's view template 2) Showing it directly
You're doing number one. What happens there is that eZ publish inserts another template where you call the "attribute_view_gui" function. Instead, you could do something like this:
"$node.object.data_map.story_intro.content"
This will return the string that is stored in that attribute. Now, you could simply pipe that string into whatever operator you want. See? (PS: If story_intro is XML text then you would have to do append a ".content.output.output_text" to the attribute. If story_intro is only text/text-line then .content is enough.)