[Python-ideas] exclusively1, common, exclusively2 = set1 - set2, set1 & set2, set2 - set1

[Shane Green]

Yeah, needs to be on sets/dictionary types otherwise question of equality versus identity comes into play.  Not to mention the behavior of shared gets pretty ambiguous: if there is one of them in one and two in the other, do two of them go in common, one in common and xor2.  I think it makes sense as a standard method of the set type, if it makes sense at all; and also that "vennsubs" might be a good name.  Could accept any itterable composed of hashable (that's what makes a viable key, righ?) items.  


On Jul 8, 2013, at 12:22 AM, Steven D'Aprano <steve at pearwood.info> wrote:

> On Sun, Jul 07, 2013 at 02:37:56PM -0700, David Mertz wrote:
>> On Jul 7, 2013 2:09 PM, "Eric V. Smith" <eric at trueblade.com> wrote:
>>> 
>>> On 7/7/2013 1:45 AM, David Mertz wrote:
>>>> Maybe the generalization isn't worthwhile.  I was thinking that maybe a
>>>> more general version should keep order in types that have order to start
>>>> with, so I confess I'm not certain what the "correct" interface would
>> be.
>>>> 
>>>> But even if it were only for sets, I like the idea of a plain function
>>>> much better than a method of a set, even if the only arguments it
>>>> accepted were sets.
>>> 
>>> If it were added, I think a classmember on set would be reasonable.
>> 
>> I agree.
> 
> A class member? Do you mean a class *method*?
> 
> I think it would be freaky and weird if I did this:
> 
> some_set.venn_split(second_set, another_set)
> 
> (for lack of a better name) and the value of some_set was ignored. Class 
> methods are okay for things like alternate constructors, but I don't 
> think they are appropriate here.
> 
> 
> 
> -- 
> Steven
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