Code Completion 4 Challenges

Complete the Python Class Subscription Code

Practice implementing __class_getitem__ for class subscription and generic-style parameterization.

Advanced ~9 min read

Implement class subscription so Box[int] returns a tuple containing the class name and the supplied item.

python Your answer

class Box:
    def __class_getitem__(cls, item):
        

print(Box[int])

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Normalize a single-or-multiple type argument into a tuple before building the result.

python Your answer

class Pair:
    def __class_getitem__(cls, key):
        if not isinstance(key, tuple):
            key = (key,)
        
        return tuple(item.__name__ for item in key)

print(Pair[int, str])

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Return a GenericAlias so Box[int] has a parameterized runtime representation.

python Your answer

from types import GenericAlias

class Box:
    def __class_getitem__(cls, item):
        

print(Box[int])
print(Box[int].__args__)

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Implement the class-level hook without changing the existing instance subscription method.

python Your answer

class Catalog:
    def __class_getitem__(cls, key):
        

    def __getitem__(self, key):
        return key * 10

print(Catalog[int])
print(Catalog()[2])

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