ScreenPyHQ#25 subclassing support for mypy prior to PEP 673 and python/mypy#11666

Author: bandophahita

screenpy/actions/make_note.py

@@ -2,13 +2,15 @@
 Make a quick note about the answer to a Question.
 """
 
-from typing import Any, Optional, Union
+from typing import Any, Optional, Type, TypeVar, Union
 
 from screenpy import Actor, Director
 from screenpy.exceptions import UnableToAct
 from screenpy.pacing import aside, beat
 from screenpy.protocols import Answerable, ErrorKeeper
 
+Self = TypeVar("Self", bound="MakeNote")
+
 
 class MakeNote:
     """Make a note of a value or the answer to a Question.
@@ -29,7 +31,7 @@ class MakeNote:
     key: Optional[str]
 
     @classmethod
-    def of(cls, question: Union[Answerable, Any]) -> "MakeNote":
+    def of(cls: Type[Self], question: Union[Answerable, Any]) -> Self:
         """Supply the Question to answer and its arguments.
 
         Aliases:
@@ -38,21 +40,21 @@ def of(cls, question: Union[Answerable, Any]) -> "MakeNote":
         return cls(question)
 
     @classmethod
-    def of_the(cls, question: Union[Answerable, Any]) -> "MakeNote":
+    def of_the(cls: Type[Self], question: Union[Answerable, Any]) -> Self:
         """Alias for :meth:`~screenpy.actions.MakeNote.of`."""
         return cls.of(question)
 
-    def as_(self, key: str) -> "MakeNote":
+    def as_(self: Self, key: str) -> Self:
         """Set the key to use to recall this noted value."""
         self.key = key
         return self
 
-    def describe(self) -> str:
+    def describe(self: Self) -> str:
         """Describe the Action in present tense."""
         return f"Make a note under {self.key}."
 
     @beat('{} jots something down under "{key}".')
-    def perform_as(self, the_actor: Actor) -> None:
+    def perform_as(self: Self, the_actor: Actor) -> None:
         """Direct the Actor to take a note."""
         if self.key is None:
             raise UnableToAct("No key was provided to name this note.")
@@ -70,7 +72,7 @@ def perform_as(self, the_actor: Actor) -> None:
         Director().notes(self.key, value)
 
     def __init__(
-        self, question: Union[Answerable, Any], key: Optional[str] = None
+        self: Self, question: Union[Answerable, Any], key: Optional[str] = None
     ) -> None:
         self.question = question
         self.key = key

screenpy/actions/pause.py

@@ -10,7 +10,7 @@
 from screenpy.exceptions import UnableToAct
 from screenpy.pacing import beat
 
-T_pause = TypeVar("T_pause", bound="Pause")
+Self = TypeVar("Self", bound="Pause")
 
 
 class Pause:
@@ -36,11 +36,11 @@ class Pause:
     time: float
 
     @classmethod
-    def for_(cls: Type[T_pause], number: float) -> T_pause:
+    def for_(cls: Type[Self], number: float) -> Self:
         """Specify how many seconds or milliseconds to wait for."""
         return cls(number)
 
-    def seconds_because(self: T_pause, reason: str) -> T_pause:
+    def seconds_because(self: Self, reason: str) -> Self:
         """Use seconds and provide a reason for the pause.
 
         Aliases:
@@ -50,23 +50,23 @@ def seconds_because(self: T_pause, reason: str) -> T_pause:
         self.reason = self._massage_reason(reason)
         return self
 
-    def second_because(self: T_pause, reason: str) -> T_pause:
+    def second_because(self: Self, reason: str) -> Self:
         """Alias for :meth:`~screenpy.actions.Pause.seconds_because`."""
         return self.seconds_because(reason)
 
-    def milliseconds_because(self: T_pause, reason: str) -> T_pause:
+    def milliseconds_because(self: Self, reason: str) -> Self:
         """Use milliseconds and provide a reason for the pause."""
         self.unit = f"millisecond{'s' if self.number != 1 else ''}"
         self.time = self.time / 1000.0
         self.reason = self._massage_reason(reason)
         return self
 
-    def describe(self: T_pause) -> str:
+    def describe(self: Self) -> str:
         """Describe the Action in present tense."""
         return f"Pause for {self.number} {self.unit} {self.reason}."
 
     @beat("{} pauses for {number} {unit} {reason}.")
-    def perform_as(self: T_pause, _: Actor) -> None:
+    def perform_as(self: Self, _: Actor) -> None:
         """Direct the Actor to take their union-mandated break."""
         if not self.reason:
             raise UnableToAct(
@@ -76,7 +76,7 @@ def perform_as(self: T_pause, _: Actor) -> None:
 
         sleep(self.time)
 
-    def _massage_reason(self: T_pause, reason: str) -> str:
+    def _massage_reason(self: Self, reason: str) -> str:
         """Apply some gentle massaging to the reason string."""
         if not reason.startswith("because"):
             reason = f"because {reason}"
@@ -85,7 +85,7 @@ def _massage_reason(self: T_pause, reason: str) -> str:
 
         return reason
 
-    def __init__(self: T_pause, number: float) -> None:
+    def __init__(self: Self, number: float) -> None:
         self.number = number
         self.time = number
         self.unit = f"second{'s' if self.number != 1 else ''}"

screenpy/actions/see.py

@@ -2,7 +2,7 @@
 Make an assertion using a Question and a Resolution.
 """
 
-from typing import Any, Union
+from typing import Any, Type, TypeVar, Union
 
 from hamcrest import assert_that
 
@@ -12,6 +12,8 @@
 from screenpy.resolutions import BaseResolution
 from screenpy.speech_tools import get_additive_description
 
+Self = TypeVar("Self", bound="See")
+
 
 class See:
     """See if a value or the answer to a Question matches the Resolution.
@@ -32,16 +34,18 @@ class See:
     """
 
     @classmethod
-    def the(cls, question: Union[Answerable, Any], resolution: BaseResolution) -> "See":
+    def the(
+        cls: Type[Self], question: Union[Answerable, Any], resolution: BaseResolution
+    ) -> Self:
         """Supply the Question (or value) and Resolution to test."""
         return cls(question, resolution)
 
-    def describe(self) -> str:
+    def describe(self: Self) -> str:
         """Describe the Action in present tense."""
         return f"See if {self.question_to_log} is {self.resolution_to_log}."
 
     @beat("{} sees if {question_to_log} is {resolution_to_log}.")
-    def perform_as(self, the_actor: Actor) -> None:
+    def perform_as(self: Self, the_actor: Actor) -> None:
         """Direct the Actor to make an observation."""
         if isinstance(self.question, Answerable):
             value: object = self.question.answered_by(the_actor)
@@ -57,7 +61,7 @@ def perform_as(self, the_actor: Actor) -> None:
         assert_that(value, self.resolution, reason)
 
     def __init__(
-        self, question: Union[Answerable, Any], resolution: BaseResolution
+        self: Self, question: Union[Answerable, Any], resolution: BaseResolution
     ) -> None:
         self.question = question
         self.question_to_log = get_additive_description(question)

screenpy/actions/see_all_of.py

@@ -3,7 +3,7 @@
 all of which are expected to be true.
 """
 
-from typing import Tuple
+from typing import Tuple, Type, TypeVar
 
 from screenpy import Actor
 from screenpy.exceptions import UnableToAct
@@ -13,6 +13,8 @@
 
 from .see import See
 
+Self = TypeVar("Self", bound="SeeAllOf")
+
 
 class SeeAllOf:
     """See if all the provided values or Questions match their Resolutions.
@@ -38,21 +40,21 @@ class SeeAllOf:
     """
 
     @classmethod
-    def the(cls, *tests: Tuple[Answerable, BaseResolution]) -> "SeeAllOf":
+    def the(cls: Type[Self], *tests: Tuple[Answerable, BaseResolution]) -> Self:
         """Supply any number of Question/value + Resolution tuples to test."""
         return cls(*tests)
 
-    def describe(self) -> str:
+    def describe(self: Self) -> str:
         """Describe the Action in present tense."""
         return f"See if all of {self.number_of_tests} tests pass."
 
     @beat("{} sees if all of the following {number_of_tests} tests pass:")
-    def perform_as(self, the_actor: Actor) -> None:
+    def perform_as(self: Self, the_actor: Actor) -> None:
         """Direct the Actor to make a series of observations."""
         for question, resolution in self.tests:
             the_actor.should(See.the(question, resolution))
 
-    def __init__(self, *tests: Tuple[Answerable, BaseResolution]) -> None:
+    def __init__(self: Self, *tests: Tuple[Answerable, BaseResolution]) -> None:
         if len(tests) < 2:
             raise UnableToAct(
                 "Must supply 2 or more tests for SeeAllOf."

screenpy/actions/see_any_of.py

@@ -3,7 +3,7 @@
 at least one of which is expected to be true.
 """
 
-from typing import Tuple
+from typing import Tuple, Type, TypeVar
 
 from screenpy import Actor
 from screenpy.exceptions import UnableToAct
@@ -13,6 +13,8 @@
 
 from .see import See
 
+Self = TypeVar("Self", bound="SeeAnyOf")
+
 
 class SeeAnyOf:
     """See if at least one value or Question matches its Resolution.
@@ -39,16 +41,16 @@ class SeeAnyOf:
     """
 
     @classmethod
-    def the(cls, *tests: Tuple[Answerable, BaseResolution]) -> "SeeAnyOf":
+    def the(cls: Type[Self], *tests: Tuple[Answerable, BaseResolution]) -> Self:
         """Supply any number of Question/value + Resolution tuples to test."""
         return cls(*tests)
 
-    def describe(self) -> str:
+    def describe(self: Self) -> str:
         """Describe the Action in present tense."""
         return f"See if any of {self.number_of_tests} tests pass."
 
     @beat("{} sees if any of the following {number_of_tests} tests pass:")
-    def perform_as(self, the_actor: Actor) -> None:
+    def perform_as(self: Self, the_actor: Actor) -> None:
         """Direct the Actor to make a series of observations."""
         none_passed = True
         for question, resolution in self.tests:
@@ -61,7 +63,7 @@ def perform_as(self, the_actor: Actor) -> None:
         if none_passed:
             raise AssertionError(f"{the_actor} did not find any expected answers!")
 
-    def __init__(self, *tests: Tuple[Answerable, BaseResolution]) -> None:
+    def __init__(self: Self, *tests: Tuple[Answerable, BaseResolution]) -> None:
         if len(tests) < 2:
             raise UnableToAct(
                 "Must supply 2 or more tests for SeeAnyOf."