[Petal] Interoperability

[Jim Fulton]

William McKee wrote:
> Hi Jim and Jean-Michel,
> 
> I've been following up on your conversation this morning and am glad to see some 
> progress being made towards interoperability. I think it would be a good thing.

Great.
...

> - The concept of TALES expressions seems like it would be an interesting way to 
> implement the Petal syntax that extends beyond the TAL spec. Unless, TALES 
> becomes a defacto standard for building templates for web applications, I'm not 
> sure what the benefits would be of doing this work. 

TALES defines minimum expression types, path and string. Templates that use just
support these expression types should be usable with Zope or a perl-based system.

> - I must agree about the dot notation. I cannot see where an application would need 
> to have a variable name with a dot in it. If I'm accepting user input, it will usu. go 
> into a variable that I have named. Backslashing special characters makes sense in 
> the exceptional cases.

You might implement collections that users can put their content into. Users will
want to pick the names within the collections. User's will want to pick names that
they are familiar with.  We have quite a bit of experience with this in Zope.


> - The debate about using Perl/Python/Java/etc. in templates vs. creating a mini-
> language will never end. I've tried many Perl template implementations. Personally, 
> I prefer a mini-language to embedding code into templates.

If you use a mini-language, then you are embedding code in the template.
Why not pick a language that exists already?

...

> - What is the Object Constraint Language? That sounds like a possibility.

It's part of the UML spec. Do a google search for "object constraint language"
and you'll get lots of links. I can't say that I've looked at it a lot. A subset
of OCL might be more appropriate here. The spec is a 775K pdf.

Jim

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