on implementing a toy oop-system

Fri Sep 23 16:59:12 EDT 2022

ram at zedat.fu-berlin.de (Stefan Ram) writes:
> Meredith Montgomery <mmontgomery at levado.to> writes:
>>Is that at all possible somehow? Alternatively, how would you do your
>>toy oop-system?
>> Maybe something along those lines:
>> from functools import partial
>> def counter_create( object ):
> object[ "n" ]= 0
> def counter_increment( object ):
> object[ "n" ]+= 1
> def counter_value( object ):
> return object[ "n" ]
>> counter_class =( counter_create, counter_increment, counter_value )
>> def inherit_from( class_, target ):
> class_[ 0 ]( target )
> for method in class_[ 1: ]:
> target[ method.__name__ ]= partial( method, target )
>> car = dict()
>> inherit_from( counter_class, car )
>> print( car[ "counter_value" ]() )
> car[ "counter_increment" ]()
> print( car[ "counter_value" ]() )
>> . The "create" part is simplified. I just wanted to show how
> to make methods like "counter_increment" act on the object
> that inherited them using "partial".

I really liked this idea. I organized it my way. Have a look. (Thank
you for the lecture!)
--8<---------------cut here---------------start------------->8---
from functools import partial
def Counter(name = None):
 o = {"name": name if name else "untitled", "n": 0}
 def inc(o):
 o["n"] += 1
 return o
 o["inc"] = inc
 def get(o):
 return o["n"]
 o["get"] = get
 return o
def Car(maker):
 o = {"maker": maker, "state": "off"}
 inherit_from(Counter, o)
 def on(o):
 if o["is_on"]():
 raise ValueError("oh, no: car is already on")
 o["inc"]()
 print(f"{o['maker']}: bruum!")
 o["state"] = "on"
 return o
 o["on"] = partial(on, o)
 def off(o):
 if o["is_off"]():
 raise ValueError("oh, no: car is already off")
 print(f"{o['maker']}: spat!")
 o["state"] = "off"
 return o
 o["off"] = partial(off, o)
 def is_on(o):
 return o["state"] == "on"
 o["is_on"] = partial(is_on, o)
 def is_off(o):
 return o["state"] == "off"
 o["is_off"] = partial(is_off, o)
 return o
def main():
 car1 = Car("Ford")
 car2 = Car("VW")
 for i in range(5):
 car1["on"](); car1["off"]()
 for i in range(3):
 car2["on"](); car2["off"]()
 print(f"car turned on = {car1['get']()} ({car1['maker']})")
 print(f"car turned on = {car2['get']()} ({car2['maker']})")
## (*) How to inherit the methods from a class
## 
def inherit_from(C, target):
 o = C()
 for k, v in o.items():
 if callable(v):
 target[k] = partial(v, target)
 else:
 target[k] = v
--8<---------------cut here---------------end--------------->8---