[Feature Request] Make beartype.typing Actually Do Something #237
Description
This feature request comes courtesy @JWCS via this secretive commit comment that has already been lost to the sands of time. @JWCS wisely notes that beartype.typing is currently undocumented, largely useless, and a pox upon the good name of @beartype:
Out of curiousity, why doesn't
beartype.typingbackport types?
I had previously expected that when I have to dip back to an earlier version of python, I can just frombeartype.typing import List, Dict, Self, Never, TypeAlias, Literal, Final, TypeGuard, Protocol, OrderedDict, without having to sort through that these, respectively (depr sometime, depr sometime, 3.11+, 3.11+, 3.8+, 3.8+, 3.10+, 3.8+, 3.7.2+), etc.
@JWCS is not wrong. beartype.typing should do considerably more for everyone. It currently doesn't, mostly because I wasn't convinced anyone even used beartype.typing – let alone wanted beartype.typing to do considerably more for everyone.
Like beartype.cave, beartype.typing is this basically undocumented thing that I quietly maintain out of a nostalgic wistfulness for the halcyon past when I was young, less bald, and enthusiastic. But you've convinced me that somebody actually cares about beartype.typing!
Thankfully, I'm convinced that what everyone wants can be done without adding typing_extensions as a mandatory runtime dependency to either @beartype or your workflow. If anyone would like to require typing_extensions in their workflow, of course, that's perfectly fine – but we won't be mandating that on @beartype's end.
What Is This Inchoate Madness You Speak Of!?
Here is what the implementation of beartype.typing should look like. It doesn't currently, because I am contemptible, degenerate, and/or an inveterate pauper. But it should:
# In "beartype.typing.__init__": the future of typing backports begins today.
from typing import TYPE_CHECKING
# If @beartype is currently being statically type-checked (e.g.,
# by mypy or pyright), just defer to the third-party
# "typing_extensions" package.
#
# Note that this does *NOT* mean that @beartype now unconditionally
# requires "typing_extensions" at either runtime or static
# type-checking time. Any code in an "if TYPE_CHECKING:" is (basically)
# just a convincing semantic lie that everything syntactically ignores.
if TYPE_CHECKING:
from typing_extensions import * # <-- heh
# Else, @beartype is currently being imported from at runtime. This is
# the common case. This is also the non-trivial case, because @beartype
# does *NOT* require "typing_extensions" as a mandatory runtime
# dependency, because @beartype requires *NOTHING* as a runtime
# dependency. This is the only rule in @beartype's Rule of Law.
else:
# Import the requisite machinery that will make the magic happen.
from beartype._util.mod.lib.utiltyping import (
import_typing_attr_or_fallback as _import_typing_attr_or_fallback)
# Dynamically define the "Self" type hint as follows:
# * If the active Python interpreter targets Python >= 3.11, just
# defer to the canonical "typing.Self" type hint.
# * Else if "typing_extensions" is importable *AND* of a sufficiently
# recent version to define the backported "typing_extensions.Self"
# type hint, fallback to that hint.
# * Else, synthesize a placeholder type hint that @beartype internally
# recognizes as semantically equivalent to "typing.Self".
Self = _import_typing_attr_or_fallback('Self', TypeHintTypeFactory(object))
#FIXME: Repeat the above logic for *ALL* existing "typing" attributes.💪 🐻 👍