[Python-Dev] PEP 372 -- Adding an ordered directory to collections ready for pronouncement

[Lie Ryan]

Gisle Aas wrote:
> On Mar 4, 2009, at 9:01 , Glenn Linderman wrote:
> 
>> On approximately 3/3/2009 11:22 PM, came the following characters from 
>> the keyboard of Raymond Hettinger:
>>>>> Perhaps the terminology should be
>>>>>
>>>>>  ordereddict -- what we have here
>>>>>
>>>>>  sorteddict -- hypothetical future type that keeps
>>>>>                itself sorted in key order
>>> +1
>>
>> -1
>>
>> Introducing the hypothetical sorteddict would serve to reduce the 
>> likelihood of ordereddict being interpreted as sorteddict among the 
>> small percentage of people that actually read the two lines that might 
>> mention it in the documentation, but wouldn't significantly aid the 
>> intuition of people who first encounter it in someone else's code.
>>
>> And without an implementation, it would otherwise be documentation 
>> noise, not signal.
> 
> Instead of introducing a sorteddict I would instead suggest that the 
> future should bring an odict with a sort method; possibly also 
> keys_sorted and items_sorted methods.
> 
> I think this would simplify things and putting these methods into the 
> odict documentation makes it clearer how it actually behaves for people 
> that just scan the method index to get an impression of what the object 
> is about.

How about making odict ordered by insertion order, then provide an 
optional argument for defining sorter? This optional argument must be a 
function/lambda/callable object and must be the first argument.

a = odict(bloh='foo', blah='faa')
a # odict([('bloh', 'foo'), ('blah', 'faa')])

b = odict(lambda a, b: (a[0] < b[0]), bloh='foo', blah='faa')
b # sorted by key: odict([('blah', 'faa'), ('bloh', 'foo')])

c = odict(lambda a, b: (a[1] < b[1]), bloh='foo', blah='faa')
c # sorted by value: odict([('blah', 'faa'), ('bloh', 'foo')])

b = odict(lambda a, b: (a[0] > b[0]), bloh='foo', blah='faa')
b # sorted by key, descending: odict([('bloh', 'foo'), ('blah', 'faa')])