I'm trying to represent something of the form "I've chosen one member of
this group, three members of that group, and nobody from the other group".
A Bag seems right for this, except that if I want to get the list of
groups, it doesn't seem to include the one with nobody:
> Bag.new-from-pairs('a' => 0, 'b' => 3)
bag(b(3))
> my $b = BagHash.new()
BagHash.new()
> $b<a> = 3
3
> $b
BagHash.new(a(3))
> $b<a> = 0
0
> $b
BagHash.new()
I was hoping for something like Python's Counter:
>>> Counter({'a': 0, 'b': 3})
Counter({'b': 3, 'a': 0})
>>> b = Counter()
>>> b['a'] = 2
>>> b
Counter({'a': 2})
>>> b['a'] = 0
>>> b
Counter({'a': 0})
I'm wondering if anyone has any bright ideas related to this. Two things
come to mind for myself: I could subclass Bag (or create a new
implementation of Baggy), but I'm not entirely sure how I'd do so sensibly
(i.e. without reimplementing basically the whole of Bag - operators,
initializers, stringifiers...); or I could create a new class which
basically contains nothing but a list and a bag whose keys are elements of
the list.
Thanks,
Phil
