[Zope-dev] Re: TALES idea: tuple unpacking

[Shane Hathaway]

Dieter Maurer wrote:
> Be very reluctant to extend TALES. Do not do it do get just
> syntactic sugar in order to save a few lines of code.

I agree that we should be wary.  Adding a feature to make something 
simpler simultaneously complicates the whole picture.  To offset that 
negative, the new feature has to be a lot better than the previous 
alternatives.  Well, here's a sample of what we'd get with prefixes in 
path expressions, all with a very minimal addition to TALES.

"call:" eliminates the need for implicitly calling things.  Purely 
explicit calling would eliminate a major class of bugs.

"format:" provides access to the same string formatting API that 
previously required importing a module.  In fact, it seems unlikely 
you'll want to import *any* modules in templates anymore.

"zope:" gives you access to a nice Zope-specific API, again without 
importing a module.

"dc:" lets you access simple Dublin Core metadata.  Perhaps "here/title" 
should even be deprecated and replaced with "here/dc:title", since it's 
more explicit and more likely to generate the expected result, yet no 
more work.

I almost forgot to mention the most compelling reason why we need 
prefixes: in Zope 3, we won't be able to fall back on implicit 
acquisition anymore, so we need something to replace it.  Here's the 
(old) proposal that explains it all--

http://dev.zope.org/Zope3/NamespacesInTemplates

You see, prefixes are meant to let you work comfortably in an otherwise 
excruciatingly explicit world. :-)

Shane