Counter Class -- Bag/Multiset

Terry Reedy tjreedy at
Fri Jan 23 10:10:20 CET 2009

bearophileHUGS at wrote:

> Also: what's the rationale of allowing negative values too?

I can guess two:
1) Nuisance to check given that Python does not have a count (0,1,2...) 
2. Useful. + = items on hand; - = items back-ordered.
Bank account go negative also ;-). So does elevation.
Similarly, an app could set 0 to mean 'desired quantity on hand', so 
non-zero count is surplus or deficit.

I might not have thought to allow this, but it seems to open new 
applications.  (This definitely makes bag or multiset inappropriate as 


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