[ZPT] Re: [Zope3-dev] Re: RFC: TALES adapters and TAL/Tales variable namespaces

[Casey Duncan]

On Wed, 19 May 2004 17:01:57 -0400
Jim Fulton <jim at zope.com> wrote:

> Casey Duncan wrote:
[..]
> > Which seems reasonable. The dotted notation seems ok, but it implies
> > that this notation is recognized in general in path expressions
> > which is confusing because it isn't. If we didn't use dots then it
> > might look like:
> >   tal:content="x/(modules/foo/bar/baz)y/z"
> 
> I'm not sure what you mean here. If the thing in the parens was a
> path expression, it would be:
> 
>    x/(modules/foo.bar/baz)y/z
> 
> IOW, modules excepts dotted names.

It does already you mean? I did not know that. Seems a bit weird, but I
can see why. Not sure I could explain it to a ZPT newbie without making
their head cave in though...
 
> > If the thing in the parenthesis is just another path expression,
> > that mitigates the need for namespaces IMO. The above could then
> > become:
> >   tal:define="baz modules/foo/bar/baz"
> >   tal:content="x/(baz)y/z"
> 
> True, but then, the obvious syntax would be:
> 
>    x/baz(y)/z
> 
> which is the top of a slippery slope. :)

Tempting but no way ;^). I still think "(baz)y" is pretty good. "baz(y)"
is a big ole can o' knarly worms.
 
> It would also make it harder to provide predefined adapter names.
> 
> We'd like to be able to define some adapters (e.g. 'zope', 'format',
> etc.) in ZCML and let people just use them in ZPT without having to
> use defines.

Ok, I see better the reasoning. Why not just have a new top-level name
like "adapters" or "adapt" so that we can avoid new language constructs?
That might also make it easier to read and only a bit more verbose. So
adapters would be a mapping of registered name=>adapter object. So the
above could be:
  
  tal:content="x/(adapters/baz)y/z"

That puts the adapters all in one big bag, but honestly I think it is
manageable. If desired, the adapters could be categorized through
traversal:

  tal:content="x/(adapters/zope/frobnob)y/z"

This seems nice and explicit to me. I don't mind typing the word
"adapters" and it's clear that it is one even if I'm not familiar with
the casting syntax. If I used it alot in one template I could just do:

  tal:define="frobnob adapters/zope/frobnob"

-Casey