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Further improve pow #6325

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merged 5 commits into from
Nov 18, 2021
Merged

Further improve pow #6325

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c9988cf
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AlexWaygood Nov 16, 2021
e5372d6
Improve `pow`
AlexWaygood Nov 16, 2021
ee79994
Improve special-casing for `complex`
AlexWaygood Nov 16, 2021
7ff423f
Fix mypy errors
AlexWaygood Nov 17, 2021
14a8b3d
Heard you liked overloads, so I got you more overloads
AlexWaygood Nov 17, 2021
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63 changes: 50 additions & 13 deletions stdlib/builtins.pyi
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Original file line number Diff line number Diff line change
Expand Up @@ -179,6 +179,9 @@ class super(object):
@overload
def __init__(self) -> None: ...

_PositiveInteger = Literal[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25]
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@AlexWaygood, could you answer a couple of my questions?

  1. As far I understand the reason to have _PositiveInteger/_NegativeInteger is because we can't create "all positive/negative ints" types, right? So by defining a Literal we have at least some type inference for small exponents.
  2. Why did you choose to stop at 25/-20? My only guess now is that it fits in one line according to the formatting rules in typeshed 😅
  3. Why wasn't 0 exponent included in _PositiveInteger? I know it wouldn't be strictly "positive" integer then but 2**0 produces int in Python and currently it is Any according to typeshed.

Thank you!

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  1. Yup, you're quite correct! There's no way (not yet, anyway) of expressing "positive integer" in a general way, but if you're calling it with literal types, they're likely to be quite small -- and this hack is better than nothing :)
  2. Yup, once again spot on! I can't remember whether this is exactly the maximum line length black will allow under the settings typeshed has in pyproject.toml -- but it's close to it, and they're nice round numbers ;)
  3. Um... good catch! No reason at all! Feel free to submit a PR correcting my oversight! 🙂

_NegativeInteger = Literal[-1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16, -17, -18, -19, -20]

class int:
@overload
def __new__(cls: Type[_T], __x: str | bytes | SupportsInt | SupportsIndex | _SupportsTrunc = ...) -> _T: ...
Expand Down Expand Up @@ -220,11 +223,15 @@ class int:
@overload
def __pow__(self, __x: int, __modulo: Literal[0]) -> NoReturn: ...
@overload
def __pow__(self, __x: Literal[2, 3, 4, 5], __modulo: int | None = ...) -> int: ...
def __pow__(self, __x: int, __modulo: int) -> int: ...
@overload
def __pow__(self, __x: _PositiveInteger, __modulo: None = ...) -> int: ...
@overload
def __pow__(self, __x: _NegativeInteger, __modulo: None = ...) -> float: ...
# positive x -> int; negative x -> float
# return type must be Any as `int | float` causes too many false-positive errors
@overload
def __pow__(self, __x: int, __modulo: int | None = ...) -> Any: ...
def __pow__(self, __x: int, __modulo: None = ...) -> Any: ...
def __rpow__(self, __x: int, __mod: int | None = ...) -> Any: ...
def __and__(self, __n: int) -> int: ...
def __or__(self, __n: int) -> int: ...
Expand Down Expand Up @@ -1282,44 +1289,74 @@ _M = TypeVar("_M", contravariant=True)
class _SupportsPow2(Protocol[_E, _T_co]):
def __pow__(self, __other: _E) -> _T_co: ...

class _SupportsPow3NoneOnly(Protocol[_E, _T_co]):
def __pow__(self, __other: _E, __modulo: None = ...) -> _T_co: ...

class _SupportsPow3(Protocol[_E, _M, _T_co]):
def __pow__(self, __other: _E, __modulo: _M) -> _T_co: ...

_SupportsSomeKindOfPow = Union[_SupportsPow2[Any, Any], _SupportsPow3NoneOnly[Any, Any], _SupportsPow3[Any, Any, Any]]

if sys.version_info >= (3, 8):
@overload
def pow(base: int, exp: int, mod: Literal[0]) -> NoReturn: ...
@overload
def pow(base: int, exp: int, mod: int) -> int: ...
@overload
def pow(base: int, exp: _PositiveInteger, mod: None = ...) -> int: ... # type: ignore[misc]
@overload
def pow(base: int, exp: _NegativeInteger, mod: None = ...) -> float: ... # type: ignore[misc]
# int base & positive-int exp -> int; int base & negative-int exp -> float
# return type must be Any as `int | float` causes too many false-positive errors
@overload
def pow(base: int, exp: int, mod: None = ...) -> Any: ...
@overload
def pow(base: int, exp: int, mod: int) -> int: ...
@overload
def pow(base: float, exp: int, mod: None = ...) -> float: ...
# float base & float exp could return float or complex
# return type must be Any as `float | complex` causes too many false-positive errors
# return type must be Any (same as complex base, complex exp),
# as `float | complex` causes too many false-positive errors
@overload
def pow(base: float, exp: complex | _SupportsSomeKindOfPow, mod: None = ...) -> Any: ...
@overload
def pow(base: float, exp: float, mod: None = ...) -> Any: ...
def pow(base: complex, exp: complex | _SupportsSomeKindOfPow, mod: None = ...) -> complex: ...
@overload
def pow(base: _SupportsPow2[_E, _T_co], exp: _E) -> _T_co: ...
def pow(base: _SupportsPow2[_E, _T_co], exp: _E, mod: None = ...) -> _T_co: ...
@overload
def pow(base: _SupportsPow3[_E, _M, _T_co], exp: _E, mod: _M) -> _T_co: ...
def pow(base: _SupportsPow3NoneOnly[_E, _T_co], exp: _E, mod: None = ...) -> _T_co: ...
@overload
def pow(base: _SupportsPow3[_E, _M, _T_co], exp: _E, mod: _M = ...) -> _T_co: ...
@overload
def pow(base: _SupportsSomeKindOfPow, exp: float, mod: None = ...) -> Any: ...
@overload
def pow(base: _SupportsSomeKindOfPow, exp: complex, mod: None = ...) -> complex: ...

else:
@overload
def pow(__base: int, __exp: int, __mod: Literal[0]) -> NoReturn: ...
@overload
def pow(__base: int, __exp: int, __mod: None = ...) -> Any: ...
@overload
def pow(__base: int, __exp: int, __mod: int) -> int: ...
@overload
def pow(__base: int, __exp: _PositiveInteger, __mod: None = ...) -> int: ... # type: ignore[misc]
@overload
def pow(__base: int, __exp: _NegativeInteger, __mod: None = ...) -> float: ... # type: ignore[misc]
@overload
def pow(__base: int, __exp: int, __mod: None = ...) -> Any: ...
@overload
def pow(__base: float, __exp: int, __mod: None = ...) -> float: ...
@overload
def pow(__base: float, __exp: float, __mod: None = ...) -> Any: ...
def pow(__base: float, __exp: complex | _SupportsSomeKindOfPow, __mod: None = ...) -> Any: ...
@overload
def pow(__base: complex, __exp: complex | _SupportsSomeKindOfPow, __mod: None = ...) -> complex: ...
@overload
def pow(__base: _SupportsPow2[_E, _T_co], __exp: _E, __mod: None = ...) -> _T_co: ...
@overload
def pow(__base: _SupportsPow3NoneOnly[_E, _T_co], __exp: _E, __mod: None = ...) -> _T_co: ...
@overload
def pow(__base: _SupportsPow3[_E, _M, _T_co], __exp: _E, __mod: _M = ...) -> _T_co: ...
@overload
def pow(__base: _SupportsPow2[_E, _T_co], __exp: _E) -> _T_co: ...
def pow(__base: _SupportsSomeKindOfPow, __exp: float, __mod: None = ...) -> Any: ...
@overload
def pow(__base: _SupportsPow3[_E, _M, _T_co], __exp: _E, __mod: _M) -> _T_co: ...
def pow(__base: _SupportsSomeKindOfPow, __exp: complex, __mod: None = ...) -> complex: ...

def quit(code: object = ...) -> NoReturn: ...

Expand Down