[Zope] - dtml tagspace

[Jim Fulton]

Jeff Bauer wrote:
> 
> Now that Andrew Kuchling has open pandora's box by
> describing in explicit detail how to "roll your own"
> dtml tags,

BTW Andrew, thanks for getting started on this.  I
owe you a detailed review.  It's on my to-do list!

> it might be a good time to discuss how
> to protect "tagspace".  Otherwise, Digital Creations
> may produce future dtml tags that will stomp user-defined
> tag names, if this becomes a popular pastime.  A simple
> convention for tag names prefixed by <whatever> could
> be reserved for user designation.
> 
> This kind of convention would also be a documentation
> aid in reading .dtml files.
> 
> Comments from the Z guys?

Here are a number of somewhat random comments:

- I don't think that there will be *so* many new tags
  written that there is a large danger of a conflict.
  There *is* some danger, so your point is certainly
  worth raising.

- New tags need not be put in the global DTML tag-space.
  
  There are basically two ways to register tags:

  - Add an entry to DocumentTemplate.String.commands
    (Andrew described this)

  - Subclass String (or some other DTML class like HTML)
    and provide a commands registry that combines the base 
    commands with your custom ones.

  The second approach doesn't affect the global tag registry.
  
  We used the second approach in Z SQL Methods (formerly
  known as Aqueduct).  SQL methods use a subclass of 
  DocumentTemplate.HTML to render SQL.  This subclass
  adds several tags that are specifically designed to make
  generation of SQL simpler.  See
  http://www.digicool.com/site/Aqueduct/Aqueduct.html#pgfId=930928

- It's likely that people will come up with cool new tags that
  should be made globally available.  If you feel especially paranoid, 
  then it wouldn't hurt to use a naming convention:

    <!--#jim.var ......-->

- There may someday be a way to define new tags and make them
  available through acquisition.  For example, maybe someday
  you'll be able to define a new tag object and insert it in a folder.
  Templates used in the folder or sub-folders would be able to use
  the new tag.  This is just speculation.

Jim

--
Jim Fulton           mailto:jim@digicool.com
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