Horrible abuse of __init_subclass__, or elegant hack?

[jak]

Il 01/04/2021 01:14, Chris Angelico ha scritto:
> I think this code makes some sort of argument in the debate about
> whether Python has too much flexibility or if it's the best
> metaprogramming toolset in the world. I'm not sure which side of the
> debate it falls on, though.
> 
> class Building:
>      resource = None
>      @classmethod
>      def __init_subclass__(bldg):
>          super().__init_subclass__()
>          print("Building:", bldg.__name__)
>          def make_recipe(recip):
>              print(recip.__name__.replace("_", " "), "is made in a",
> bldg.__name__.replace("_", " "))
>          bldg.__init_subclass__ = classmethod(make_recipe)
> 
> 
> class Extractor(Building): ...
> class Refinery(Building): ...
> 
> class Crude(Extractor):
>      resource = "Oil"
>      time: 1
>      Crude: 1
> 
> class Plastic(Refinery):
>      Crude: 3
>      time: 6
>      Residue: 1
>      Plastic: 2
> 
> class Rubber(Refinery):
>      Crude: 3
>      time: 6
>      Residue: 2
>      Rubber: 2
> 
> Full code is here if you want context:
> https://github.com/Rosuav/shed/blob/master/satisfactory-production.py
> 
> Subclassing Building defines a class that is a building. (The ellipsis
> body is a placeholder; I haven't implemented stuff where the buildings
> know about their power consumptions and such. Eventually they'll have
> other attributes.) But subclassing a building defines a recipe that is
> produced in that building. Markers placed before the "time" are
> ingredients, those after the "time" are products.
> 
> There are actually a lot of interesting wrinkles to trying to replace
> __init_subclass__ on the fly. Things get quite entertaining if you
> don't use the decorator, or if you define and decorate the function
> outside of the class, or various other combinations.
> 
> On a scale of 1 to "submit this to The Daily WTF immediately", how bad
> is this code? :)
> 
> ChrisA
> 

Hi,
from https://github.com/Rosuav/shed/blob/master/satisfactory-production.py
I get this error:

cmd console Win10:
$> py -V
Python 3.8.6

$> py CrisAngelico.py
Building: Extractor
Building: Refinery
Building: Blender
Building: Packager
Building: Assembler
Crude is made in a Extractor
Water is made in a Extractor
Plastic is made in a Refinery
Rubber is made in a Refinery
Traceback (most recent call last):
   File "CrisAngelico.py", line 123, in <module>
     class Rubber(Refinery):
   File "CrisAngelico.py", line 72, in make_recipe
     if net <= alternate["makes"] and costs >= alternate["costs"]:
TypeError: '<=' not supported between instances of 'Counter' and 'Counter'

:^(