[Python-ideas] Proposal for extending the collections module - bags / multisets, ordered sets / unique lists

[Michael Lenzen]

On 07/18/2009 03:19 PM, Leonardo Santagada wrote:
>
> I was silent on this because I wanted someone that has a say in this
> stuff to stop it but as you really think this is important I have to
> point out that this function is probably unaceptable, it makes code that
> much harder to read (instead of set or list I have to see each parameter
> and form on my mind what they map to) and also GvR already said before
> that he doesn't like functions that have flags that make them do
> completely different things based on those.
>
> Multiset seems interesting, some of the ABCs you mentioned seems to be
> just over engineering (maybe they just need a better justification) but
> this function in my view is unacceptable.
>
> --
> Leonardo Santagada
> santagada at gmail.com
>
>
>

Thanks, this is why I posted here before I proposed anything formally, I 
wasn't aware of the precedence.  Maybe I didn't explain it clearly 
enough, or maybe I'm just wrong.

The Collection ABC was mostly to unify operations of the different 
collections for the collection function, so that a generic collection 
returned by the collection function meant something, you wouldn't have 
to look back to see how it will perform.  For example all collections 
would have to provide a count(elem) method, or all mutable collections 
could have to provide add and remove methods.

I don't understand how this code becomes unreadable.

  > hand = collection(ordered=False, unique=False)
  > for i in range(5):
  >     hand.add(deck.pop_card())
  > for card in cards:
  >     if hand.count(card) == 2:
  >         print('You have a pair.')

-Michael Lenzen