Disappearing Tags

Problem

Several people don’t like the fact that their pages end up littered with <span> tags that they had to add in order to hold tal:repeat. Not all (not many?) XML schemas provide a “neutral” tag like <span> and <div>, so it might be impossible to cleanly generate documents in those schemas.

Proposal

These proposals aren’t mutually exclusive, and #2 will not solve the problem for XML, so both may be implemented.

1. Define a <tal:block> tag that is always replaced by its contents.

   Also, since the default namespace of its attributes is tal:, we can omit it from the attributes. We would get 1 2 3 from:

   <tal:block repeat="digit python:1,2,3">
     <tal:block replace="digit">1</tal:block>
   </tal:block>
   

   Testing has shown that Dreamweaver and GoLive, at least, have no problem with tal:block tags.

2. Add a statement called tal:remove or tal:no_tag that replaces the statement’s tag with its children, after other TAL processing is done. The attribute value could be a boolean expression that controls whether the tag is removed, or omitted for the default behaviour. For example:

   <span tal:repeat="digit python:1,2,3"
         tal:remove="">
         <span tal:replace="digit">1</span>
   </span>
   
   <span tal:repeat="digit python:1,2,3"
         tal:no_tag="options/no_tags">
                 <span tal:replace="digit">1</span>
   </span>
   

Comments

(Earlier comments consolidated)

mindlace (Jun 17, 2001 4:02 am; Comment #1) –

Note that the block syntax would also allow me to use ZPT for things like CSS. I think the “big problem” with your own tags in DTML was things like if else /if , where the “middle” tag was a singleton, and no editor would be able to know if it should keep else.

From a pedantic perspective, having a block tag also lets TAL be a real schema as opposed to this floating attribute namespace.

byron (Jun 18, 2001 6:00 pm; Comment #9) –

Is there a missing double quote after tal:replace=”digit in the examples, or is that the syntax?

Evan - whoops, no, it’s a typo. Fixed now

richard (Jul 14, 2001 10:39 pm; Comment #10) –

+1

peterbe (Jul 16, 2001 3:28 am; Comment #11) Editor Remark Requested –

+1 This is cool and necessary for survival for those XML Schemas you’re talking about. Please explain/discuss the possible values of the tal:remove attribute a bit more.

mindlace (Jul 18, 2001 1:40 pm; Comment #12) –

+6 :)

mindlace (Jul 18, 2001 1:42 pm; Comment #13) –

er… that goes for proposal 1. I’m indifferent about #2.

n.larosa (Jul 30, 2001 9:05 am; Comment #14) –

+1 for proposal #2. I would avoid the introduction of new tags, everything in attributes is cleaner.

This would be clean up the generated pages a lot. Also, often there are <div></div> empty tags that cannot be avoided, so I would like to see three values for the tal:remove attribute: yes, no and empty. The empty value would instruct the parser to only erase the tag if it is empty.

poster (Jul 30, 2001 10:41 pm; Comment #15) –

Proposal 1: +1

this seems necessary for a robust templating system (XML, as noted above), and acknowledges that it is structural logic and not a display tag; I would suggest this to be the last-resort method, preferring my alternate proposal below.

Proposal 2: -1

Pure structural logic masquerading as actual document markup is not only redundant but potentially confusing, and somewhat against the “What you see is very similar to what you get” ZPT principle. Of course, this argument could also be made against tal:replace as an attribute and not a tag… In any case, tal:remove would also significantly overlap tal:replace in functionality.

Alternate proposal to proposal 2: tal:repeat_internal

The situation in which the noted problem arises is in repeats. If a tag attribute is available that repeats only its internal contents, I believe many situations could be resolved more gracefully. In an example modified from one in Evan’s “Getting Started” tutorial, the tbody tag would not be endlessly and pointlessly repeated in the produced code, for instance:

<table><tr><th>Titles</th></tr>
  <tbody tal:repeat_internal="item container/objectValues">
  <tr bgcolor="#EEEEEE" tal:condition="repeat/item/even">
    <td tal:content="item/title">a title</td></tr>
    <tr tal:condition="repeat/item/odd">
    <td tal:content="item/title">a title</td></tr>
  </tbody>
</table>

bernt (Aug 12, 2001 9:13 am; Comment #17) –

See Default Content Variable Problem and Proposal for a related problem and an alternate solution.