[ZPT] v2 of Path Prefixes in CVS

[Fergal Daly]

On Sunday 31 August 2003 23:12, Evan Simpson wrote:
> Fergal Daly wrote:
> The scope is global.  Zope 3 will have facilities for defining prefixes 
> in an entire site, or package, or whatever level is most appropriate. 
> Zope 2 doesn't really have the machinery to do this right.

Fair enough. So for Zope 3 people won't need to define prefixes in their 
templates but for Zope 2 people will either have to define the "dc:" prefix 
in every template that uses it or have some sort of include templates.

> That example doesn't give a good feel for typical usage.  In Zope 3, it 
> will commonly be used to access Dublin Core properties, as in 
> "here/myDocument/dc:title".  Among the builtins in Zope 2 we have 
> 'item:' for integer item access, as in "options/a_list/item:1".  This 
> does not fit well into your argument-passing form.

dc:title seems a better example as it feels like dc:title is a property of the 
here/myDocument. It just seems that the feature is open to abuse as a way of 
getting around the lack of arguments in method calls.

If all lists had an item method then options/a_list/item(1) would be perfectly 
natural. Not being a python user I was a little surprised to find out that 
lists don't have a named method for setting and getting items. What do you do 
when you want to create an object that appears to be a list? Do you have to 
resort to icky stuff similar to Perl's tie functionality?

In both these cases prefixes seem to be a way of calling a method that should 
be available already but aren't for some reason, that is lists should have 
accessor methods and documents should support Dublin core. That's useful and 
it's a pity languages don't allow that as easily.

> > If you're going to do it, it would be better to use a different character 
to 
> > separate "foo/bar" and "my", space for instance.
> 
> Spaces and parens are valid characters in Zope object names, and 
> therefore in path segments. In any case, the syntax is not likely to 
> change, given the existing Zope 3 implementation.

Space was chosen at random, I didn't look up the docs out of laziness. "/" 
makes sense from the accessing a propertly point of view.

> Unless you use longish prefix names, it should be quite easy to get into 
> the habit of visually parsing "/pname:arg/".

foo/bar/p:arg is not so bad when p:arg is a "property" of foor/bar, so 
something like page/filename/file:owner wouldn't be so bad but things where 
you calculate something from the argument like 
foo/size/math:sqrt/other:mangle has the potential for lots of badness and 
would be better written using a method calling syntax,

F