[Zope] dtml-in sort by generic function

[Oleg Broytmann]

Hello!

   I returned to the idea after spending some time with bugs in b2; all was
fixed in b3 at last. I am ready to start coding and patching dtml-in.

On Wed, 14 Mar 2001, Dieter Maurer wrote:
> I am not yet clear about a good syntax. It
> should be something, that pairs the attribute with the sorting
> function essential for this attribute: something like:
>
> 	 sort="attr1[cmp1],attr2,attr3[cmp3],...."
>
> This should mean, use "cmp1" for "attr1", the default comparison
> for "attr2" (i.e. cmp) and "cmp3" for "attr3" (and so on).

> Each "cmp" is looked up in the namespace and if not found there,
> in a standard set of comparison function, such that it is
> easy to get "locale_asc", "locale_desc", "case_insensitive_asc", ....

   As I already said, this looks good... but I don't want to have a
predefined set of names. I want these "locale_asc"/"locale_desc" to be the
real functions. And I don't want to have 2 almost identical functions
(asc/desc) for every comparison function. So I am thinking about syntax
like this:

   sort="attr1/cmp1,attr2,attr3/cmp3/desc,...."

That is, attribute/function/direction. Default direction is ASC, of course.
It would be easy to modify the generic function you've provided:

>   def lexicographicCompare(values1,values2,functions):
>     '''*values1*, *values2* and *functions* are all tuples of the
>     same length with "functions[i]" capable of comparing
>     "value1[i]" and "values2[i]".
>     The result is the lexicographic comparison of the tuples.'''
>     for v1,v2,cmp in map(None,value1,value2,functions):
>       c= cmp(v1,v2) # maybe we should do something, if this raises an exception
>       if c: return c
>     return 0

Oleg.
----
     Oleg Broytmann     http://www.zope.org/Members/phd/     phd@phd.pp.ru
           Programmers don't die, they just GOSUB without RETURN.