[Dev] AttributeCollaters

[Alec Flett]

Ok, its an awkward term. But here's the concept: It would be nice if 
there were a well-known way of sorting, grouping, and comparing 
particular attributes, and choosing a particular well-known method if 
there are multiple ways.

I have a need for this in the Table Summary View's sections. Basically, 
I'd like to be able to "group" by date - make sections for dates based 
on an arbitrary, domain-specific grouping that is consistent with some 
particular sorting. I'd like to create groups for "Today", "Yesterday", 
"This week" and so forth.

The way I determine the "division points" for a list of items by passing 
in a "key" function to a function called get_divisions(). The key() 
function returns the grouping key. At the moment, the table code looks 
exactly like this:

indexName = self.blockItem.contents.indexName
self.sectionIndexes = get_divisions(self.blockItem.contents, key=lambda 
x: getattr(x, indexName))

What I'd like to do is have a function specifically for the "date" 
column, something like:

function date_group_key(item):
    date = item.date
    if (isToday(date)): return "Today"
    if (isThisWeek(date)): return "ThisWeek"
   etc...

And then my call to get_divisions looks like this:

self.sectionIndexes = get_divisions(self.blockItem.contents, 
key=date_group_key)

Further, I need to be able to indicate to a sorting algorithm which 
values come "First" - for example in triageStatus, the 'proper' order is 
'now', 'later', 'done' even though alphabetically they are in a 
different order (it so happens they are in reverse, but thats not 
important.. and yes we also need to translate these into the appropriate 
language - thats a separate but related problem)

What I want is a dynamic way to look up these functions based on some 
set of criteria such as "I need to make sections" or "I need to sort 
triage status"

Anyone have ideas here? I'd like to leverage some of the AttributeEditor 
getSingleton() stuff, even if only in concept.


Alec