[Python] singledispatchmethod for list[str] or list[int]

I'm trying to overload a method with singledispatchmethod. It works great for simple types like int and str, but for nested types like list[int], this breaks with the following error.

TypeError: Invalid annotation for 'value'. list[int] is not a class.


How can I handle this nested type when registering a specific-type method?

I know there is an option for using the multimethod package, but I'm looking for a native base Python solution.

from functools import singledispatchmethod

class Processor:
@singledispatchmethod
def process(self, value):
print(f"Default processing for {value}")

@process.register
def _(self, value: int):
print(f"Processing an integer: {value}")

@process.register
def _(self, value: str):
print(f"Processing a string: {value}")

@process.register
def _(self, value: list[int]):
print(f"Processing a list of integers: {value}")

@process.register
def _(self, value: list[str]):
print(f"Processing a list of strings: {value}")

# Example usage:
p = Processor()
p.process(10) # Processing an integer: 10
p.process("hello") # Processing a string: hello
p.process([1, 2, 3]) # Processing a list: [1, 2, 3]
p.process(["a", "b", "c"]) # Processing a list of strings: ['a', 'b', 'c']

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