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gh-104050: Add type annotations to sentinels in Argument Clinic #104589

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gh-104050: Add type annotations to sentinels in Argument Clinic #104589

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3b12493
gh-104050: Add type annotations to sentinels in Argument Clinic
erlend-aasland May 16, 2023
5c1c2df
Merge branch 'main' into typed-clinic/sentinels
AlexWaygood May 17, 2023
d145ff8
Fix stuff
erlend-aasland May 18, 2023
5833421
Revert unneeded change
erlend-aasland May 18, 2023
703c417
Fix local rebase and write nicer if for line 2700
erlend-aasland May 18, 2023
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50 changes: 30 additions & 20 deletions Tools/clinic/clinic.py
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
import contextlib
import copy
import cpp
import enum
import functools
import hashlib
import inspect
Expand All @@ -28,7 +29,15 @@

from collections.abc import Callable
from types import FunctionType, NoneType
from typing import Any, NamedTuple, NoReturn, Literal, overload
from typing import (
Any,
Final,
Literal,
NamedTuple,
NoReturn,
Type,
overload,
)

# TODO:
#
Expand Down Expand Up @@ -58,25 +67,21 @@
"return_value",
}

class Unspecified:
def __repr__(self) -> str:
return '<Unspecified>'

unspecified = Unspecified()

class Sentinels(enum.Enum):
unspecified = "unspecified"
NULL = "null"
unknown = "unknown"

class Null:
def __repr__(self) -> str:
return '<Null>'

NULL = Null()
return f"<{self.value.capitalize()}>"


class Unknown:
def __repr__(self) -> str:
return '<Unknown>'
unspecified: Final = Sentinels.unspecified
NULL: Final = Sentinels.NULL
unknown: Final = Sentinels.unknown

unknown = Unknown()
NullType = type(Sentinels.NULL)
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@AlexWaygood AlexWaygood May 18, 2023 •
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Hmm, The type of Sentinels.Null is just Sentinels. For Python enums, all enum members are instances of the enum class. (This is why I was wondering if maybe the Null class should just be left as it is; it maybe needs to be its own class, rather than sharing the same class as the other sentinel values.)

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Oh, you're right.

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Perhaps we should amend this instead:

cpython/Tools/clinic/clinic.py

Lines 2605 to 2607 in dcdc90d

# If not None, default must be isinstance() of this type.
# (You can also specify a tuple of types.)
default_type: bltns.type[Any] | tuple[bltns.type[Any], ...] | None = None

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I think my approach is fundamentally flawed. This is pretty simple really: we simply want distinct (sentinel) types for default_type and the instance check (🥁).

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I'm not sure if we're in agreement or not (possibly my brain's going fuzzy at the end of a long day 😆), but I think for this PR, I might keep the refactor for unspecified and unknown, but leave Null as it is on main.

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Fab, thanks!

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The annotation for default_type is probably also incorrect.

cpython/Tools/clinic/clinic.py

Lines 2598 to 2607 in dcdc90d

# The Python default value for this parameter, as a Python value.
# Or the magic value "unspecified" if there is no default.
# Or the magic value "unknown" if this value is a cannot be evaluated
# at Argument-Clinic-preprocessing time (but is presumed to be valid
# at runtime).
default: bool | Unspecified = unspecified
# If not None, default must be isinstance() of this type.
# (You can also specify a tuple of types.)
default_type: bltns.type[Any] | tuple[bltns.type[Any], ...] | None = None

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@AlexWaygood AlexWaygood May 18, 2023 •
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The annotation for default_type is probably also incorrect.

It looks correct to me based on the comment and usage. But maybe I'm not seeing something. What makes you think it's incorrect?

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With a custom converter, you can override pretty much anything (AFAIK), so I think bltns.type[Any] is too narrow. I might be wrong.

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The comment indicates that default has to be an instance of default_type if default_type is not None, and isintance(x, Foo) for any given x will fail if Foo is not an instance of type or a tuple of objects which are instances of type


sig_end_marker = '--'

Expand Down Expand Up @@ -2690,7 +2695,7 @@ def __init__(self,
*, # Keyword only args:
c_default: str | None = None,
py_default: str | None = None,
annotation: str | Unspecified = unspecified,
annotation: str | Literal[Sentinels.unspecified] = unspecified,
unused: bool = False,
**kwargs
):
Expand All @@ -2699,7 +2704,12 @@ def __init__(self,
self.unused = unused

if default is not unspecified:
if self.default_type and not isinstance(default, (self.default_type, Unknown)):
if (self.default_type
and not (
isinstance(default, self.default_type)
or default is unknown
)
):
if isinstance(self.default_type, type):
types_str = self.default_type.__name__
else:
Expand Down Expand Up @@ -3487,7 +3497,7 @@ def str_converter_key(types, encoding, zeroes):

class str_converter(CConverter):
type = 'const char *'
default_type = (str, Null, NoneType)
default_type = (str, NullType, NoneType)
format_unit = 's'

def converter_init(
Expand All @@ -3506,7 +3516,7 @@ def converter_init(
self.format_unit = format_unit
self.length = bool(zeroes)
if encoding:
if self.default not in (Null, None, unspecified):
if self.default not in (NULL, None, unspecified):
fail("str_converter: Argument Clinic doesn't support default values for encoded strings")
self.encoding = encoding
self.type = 'char *'
Expand Down Expand Up @@ -3654,7 +3664,7 @@ def parse_arg(self, argname: str, displayname: str) -> str:

class unicode_converter(CConverter):
type = 'PyObject *'
default_type = (str, Null, NoneType)
default_type = (str, NullType, NoneType)
format_unit = 'U'

def parse_arg(self, argname: str, displayname: str) -> str:
Expand All @@ -3678,7 +3688,7 @@ def parse_arg(self, argname: str, displayname: str) -> str:
@add_legacy_c_converter('Z#', accept={str, NoneType}, zeroes=True)
class Py_UNICODE_converter(CConverter):
type = 'const Py_UNICODE *'
default_type = (str, Null, NoneType)
default_type = (str, NullType, NoneType)

def converter_init(
self, *,
Expand Down