[HN Gopher] Python Negatypes (2021)
       ___________________________________________________________________
        
       Python Negatypes (2021)
        
       Author : pcr910303
       Score  : 35 points
       Date   : 2022-07-09 12:26 UTC (10 hours ago)
        
 (HTM) web link (www.hillelwayne.com)
 (TXT) w3m dump (www.hillelwayne.com)
        
       | hwayne wrote:
       | Fun followup: turns out that `__subclasshook__` interacts with
       | the new pattern matching. I'm writing a short piece on that now.
        
       | smitty1e wrote:
       | > How is this useful?
       | 
       | It seems as though we're talking about a `filter` at the type
       | level.
       | 
       | Whatever properties we might like to prove about a random set of
       | types would seem more easily expressed in a positive, rather than
       | negative, mode.
        
       | btown wrote:
       | `__subclasshook__` is super useful if you're trying to pass a
       | mock when unit testing code that (despite this not being a best
       | practice) checks its inputs with isinstance _and_ checks for a
       | class that is far more complex to instantiate than would be wise
       | for your test. I can 't say I've ever seen it used outside of
       | testing code before, though.
        
       ___________________________________________________________________
       (page generated 2022-07-09 23:02 UTC)