[ZPT] Possible changes to path-related

[Evan Simpson]

From: "Guido van Rossum" <guido@digicool.com>
> Evan, it would seem that you need changes to the TAL interpreter to
> implement cancellation of actions, right?  Have you done this yet?

I have an untested implementation in my sandbox.  I can check it in if you
would be willing to finish/correct/test it today or tomorrow.

> I'm a bit uncomfortable with the three-way possible outcomes (do it,
> exception, or cancel), and with the scope of cancellation if
> multiple actions are placed on the same element.

I'm not sure what you mean.  I expect that any of the three outcomes might
be desired under different circumstances, and that per-action granularity is
a requirement (replace attribute A if a value exists for it, but replace
attribute B no matter what you do with A).

> I'm not at all sure I like the use of "if" in this syntax -- the
> placement of "if" in the guts of the expression to control the whole
> statement makes me think of Perl. :-)  But I don't have an
> alternative... :-(

Neither do I.  There are lots of ways I can think of to spell it, none of
them great. This at least has the virtue of being short and reading fairly
well.

Cheers,

Evan @ digicool