[ZPT] Re: zope3-dev proposal on changing implicitly calling

[Stuart Bishop]

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On Thursday, July 17, 2003, at 02:53  AM, Evan Simpson wrote:

> Florent Guillaume wrote:
>> To be honest, this sucks. I've always wanted to write
>>    context/somefunc/something/etc
>> and have TALES realize that somefunc, being a method, is callable and
>> couldn't possibly have a 'something' attribute or key.
>
> Can we get some concrete examples, to nail down this use case?  I 
> would have no trouble with auto-calling objects that have type 
> 'function' or 'instance method', since these are not legitimate 
> candidates for attribute or key access.  How often are these useful in 
> the middle of a path, though?  It's much more common in Zope for a 
> callable class instance to have a number of interesting attributes and 
> even act as a mapping.

I have a method 'getOntology' that returns the Ontology object
being used by our system. My page templates need to
access here.getOntology()['term_id'].descriptionAsHtml().
This cannot be written in a single TALES expression. I work around
it using ontology = ComputedAttribute(getOntology,1) in the object
that defines getOntology to work around this.

A method in the middle of a TALES path could always be called,
unless you really want to allow here/method/__doc__ (which shouldn't
be allowed, as we can't set security on method.__doc__). But the TALES
would break if someone replaced the method with an Object implementing
__call__

> I've come to the conclusion that it was a mistake for us not to set up 
> a proper escape mechanism for TALES from the very beginning.  We 
> should have required that any characters other than alphanumeric, 
> space, and ".-_" characters be escaped with backslashes.  Then we 
> would be free, now, to allow "context/somefunc()/something" while 
> still supporting "context/somefile\(\)/something".

A new TALES v2 XML namespace could always be defined, which would switch
on any new rules.

- -- 
Stuart Bishop <zen at shangri-la.dropbear.id.au>
http://shangri-la.dropbear.id.au/

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