audrey.feldroy.com

The experimental notebooks of Audrey M. Roy Greenfeld. This website and all its notebooks are open-source at github.com/audreyfeldroy/audrey.feldroy.com

# Delegates Decorator

by Audrey M. Roy Greenfeld | Mon, Jul 29, 2024

My study of the `@delegates` decorator and `GetAttr` from `fastcore`.

I follow https://www.fast.ai/posts/2019-08-06-delegation.html

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

class Student(Person):
    def __init__(self, name, age, grade):
        super().__init__(name, age)
        self.grade = grade

student = Student("Alice", 12, 'A')
print(student.name, student.age, student.grade)

kid = Student("Uma", 5.5, 'Good Kid!')
print(kid.name, kid.age, kid.grade)

%pip install fastcore

from fastcore.meta import delegates

class Person:
    def __init__(self, name, age, **kwargs):
        self.name = name
        self.age = age

@delegates()
class Student(Person):
    def __init__(self, name, age, grade, **kwargs):
        super().__init__(name, age, **kwargs)
        self.grade = grade

child = Student("Amira", 6, grade='A', school='XYZ')
child.__dict__

{'name': 'Amira', 'age': 6, 'grade': 'A'}

from fastcore.basics import GetAttr

class Strawberry(GetAttr):
    def __init__(self, color, variety):
        self.color, self.variety = color, variety
        self.default = color

s = Strawberry('red', 'Pegasus')
s.color, s.variety, s.default

('red', 'Pegasus', 'red')

[s for s in dir(s) if not s.startswith('_')]

['capitalize', 'casefold', 'center', 'color', 'count', 'default', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'format_map', 'index', 'isalnum', 'isalpha', 'isascii', 'isdecimal', 'isdigit', 'isidentifier', 'islower', 'isnumeric', 'isprintable', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'maketrans', 'partition', 'removeprefix', 'removesuffix', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'variety', 'zfill']

def play(game, player='Daddy', num_players=2):
    print(f'{player} is playing {game}')

play('chess', 'Mehdiya')

@delegates(play)
def play_chess(player, speed='blitz', **kwargs):
    play('chess', player)

play_chess('Uma')

print(play_chess.__signature__)

import inspect
print(inspect.signature(play_chess))

print(inspect.signature(play))