muutils.kappa

 1"""anonymous getitem class
 2
 3util for constructing a class which has a getitem method which just calls a function
 4
 5a `lambda` is an anonymous function: kappa is the letter before lambda in the greek alphabet,
 6hence the name of this class"""
 7
 8from __future__ import annotations
 9
10from typing import Callable, Final, Mapping, TypeVar
11
12_kappa_K = TypeVar("_kappa_K")
13_kappa_V = TypeVar("_kappa_V")
14
15# get the docstring of this file
16_BASE_DOC: Final[str] = (
17    # TYPING: type checkers complain here, they have no idea that this module does in fact have a __doc__
18    __doc__
19    or "anonymous getitem class"
20    + """
21
22source function docstring:
23==============================\n
24"""
25)
26
27
28class Kappa(Mapping[_kappa_K, _kappa_V]):
29    def __init__(self, func_getitem: Callable[[_kappa_K], _kappa_V]) -> None:
30        self.func_getitem = func_getitem
31        self.doc = _BASE_DOC + str(
32            getattr(
33                func_getitem, "__doc__", "<no docstring provided for source function>"
34            )
35        )
36
37    def __getitem__(self, x: _kappa_K) -> _kappa_V:
38        return self.func_getitem(x)
39
40    def __iter__(self) -> None:  # type: ignore[override]
41        raise NotImplementedError(
42            "This method is not implemented for Kappa, we don't know the valid inputs"
43        )
44
45    def __len__(self) -> int:
46        raise NotImplementedError(
47            "This method is not implemented for Kappa, no idea how many valid inputs there are"
48        )