[ZPT] Possible changes to path-related

[Evan Simpson]

From: "R. David Murray " <bitz@bitdance.com>
> I don't like 'if', but I don't have a better suggestion.

The only thing I've been able to think of, and I don't really like it,
is to get wordy:

(use-if-exists)
(use-if-true)
(exists?)

I think about these modifier using an analogy to Python.  I translate as
follows (ZPT spelling on the first line, then Python spelling):

tal:action="path:foo"
action(foo)

tal:action="path:(if) foo"
if foo:
    action(foo)

tal:action="path:(exists) foo"
action(exists('foo'))

tal:action="path:(if exists) foo"
if exists('foo'):
    action(foo)

Cheers,

Evan @ digicool