🔒 [typing] Create new class dynamically from old class

[karmic fractal]

how would you dynamically create a new class based on an old one with some mapping logic? e.g. convert TypeA to TypeB programatically, where the logic says "replace all string fields with numbers"

class TypeA:
  field1: str
  field2: bool

# -->
class TypeB:
  field1: int
  field2: bool

[novel finch]

@karmic fractal

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[karmic fractal]

in typescript you would use generics + mapping, e.g.

type TypeA = {
  field1: string
  field2: boolean
}

type X<T> = {
  [K in keyof T]: T[K] extends string ? number : T[K]
}

type TypeB = X<TypeA>
//     ^? type TypeB = { field1: number; field2: bool…

ive tried asking Claude and ChatGPT but they both tap out pretty early when it comes to anything type-system related

[rocky ruin]

Python's type system is very rudimentary. I don't think a Typescript equivalent of this is possible

[misty epoch]

well, python is not statically typed, and the existing type hinting is limited. so I wouldn't be surprised if such a thing isn't possible.

you'd probably just write a second class... or use a generic for those fields.

[steep jetty]

If you're using dataclasses, you can access dataclass_fields and just recreate it from that

There's also a variety of other options you can use to dynamically generate classes in python. type itself is a base fallback. You can also look into libraries like attrs which provide this as a major feature

However, I agree that it's unlikely you'll be able to type hint this

type hinting generated classes is a fiendish problem at the best of times, and given that it's relatively trivial to make nondeterministic most type checkers in python simply don't try

[dusky egret]

the best way I can think of would be just ```py
class TypeBase[T]:
field1: T
field2: bool

TypeA = TypeBase[str]
TypeB = TypeBase[int]

[novel finch]

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