Re: [Cheetahtemplate-discuss] what to do with varNotFound_handler

[Chuck E. <Chu...@ya...>]

At 11:10 PM 8/8/2001 -0700, Tavis Rudd wrote:
>Hi,
>I'm going to play the devil's advocate and argue against
>varNotFound_handler for the time-being, although I think I
>like it.

I'll play Cheetah-users' advocate.  :-)


>* Why do you consider it necessary?

Because in both my publishing systems (I have 2 now: A whiz bang one for 
the consulting job and a homebrew one), I want the system to do it's best 
to spew me my web site.

And because down the line, I will discover other useful things to do with 
this hook to enhance my applications.


>* Why is it a neat 'feature'?

As a hook, I can do even more. For example, I could generate a report 
stating what documents had problems and what variables weren't found. I 
could even provide links to the documents complete with an anchor to take 
me straight to the error.


>* In what real-world situations would it be useful?

You still get to see your page (eg output), even if it's not perfect. 
That's useful for demos, bootstrapping, show the boss your 
work-in-progress, ...

Plus you will get bugged on the list every 4 weeks by a newbie who asks 
"How can I customize what happens when [a] a variable is not found and [b] 
a variable value is None?"  :-)


>* Isn't it safer for an explicit exception to be
>raised, as it would be in Python when a var is referrenced
>before it is declared?

Publishing!=Programming. When I'm perusing the draft version of my site, 
one "not found error" is not a deal breaker.

Each app should be able to make this decision.


>* Should it work with $placeholders that contain normal
>Python syntax (brackets, slices, etc.) as well?

That would be nice for consistency reasons.


>*What happens when the varNotFound is inside a $funcCall()
>or an #if $test directive?  Should varNotFound only be used
>with the top-level $placeholder tags that are outside
>#directives?

I could certainly live with the hook being only for the purposes of 
output/substitution. #if's and $func()s can be wary of the issue by using 
hasName(). On the other hand, invoking hasName() for every $var in every 
template is tedious and then begs for either a Cheetah enhancement or a 
Cheetah-preprocessor.


BTW You obviously thought this was a good idea at some point because you 
were the one who put it in.  ;-)


-Chuck