Enhancement: ParsedSignature to enable TypeVar expansion using signature namespace

[haryle]

Enhancement: ParsedSignature to enable TypeVar expansion using signature namespace

[peterschutt]

You are more than welcome to make a PR, cheers.

To make it easier to review I'd first suggest creating a minimal example (I'm talking about something we can copy and paste and run without any extra work) that demonstrates the issue against main. Then we have some context when reviewing the PR.

[peterschutt]

We have

litestar/litestar/utils/typing.py

Lines 233 to 262 in ef9dbb7

	def get_type_hints_with_generics_resolved(
	annotation: Any,
	globalns: dict[str, Any] | None = None,
	localns: dict[str, Any] | None = None,
	include_extras: bool = False,
	type_hints: dict[str, Any] | None = None,
	) -> dict[str, Any]:
	"""Get the type hints for the given object after resolving the generic types as much as possible.
	Args:
	annotation: A type annotation.
	globalns: The global namespace.
	localns: The local namespace.
	include_extras: A flag indicating whether to include the ``Annotated[T, ...]`` or not.
	type_hints: Already resolved type hints
	"""
	origin = get_origin(annotation)
	if origin is None:
	# Implies the generic types have not been specified in the annotation
	if type_hints is None: # pragma: no cover
	type_hints = get_type_hints(annotation, globalns=globalns, localns=localns, include_extras=include_extras)
	typevar_map = {p: p for p in annotation.__parameters__}
	else:
	if type_hints is None: # pragma: no cover
	type_hints = get_type_hints(origin, globalns=globalns, localns=localns, include_extras=include_extras)
	# the __parameters__ is only available on the origin itself and not the annotation
	typevar_map = dict(zip(origin.__parameters__, get_args(annotation)))
	return {n: _substitute_typevars(type_, typevar_map) for n, type_ in type_hints.items()}

[haryle]

We have

litestar/litestar/utils/typing.py

Lines 233 to 262 in ef9dbb7

	def get_type_hints_with_generics_resolved(
	annotation: Any,
	globalns: dict[str, Any] | None = None,
	localns: dict[str, Any] | None = None,
	include_extras: bool = False,
	type_hints: dict[str, Any] | None = None,
	) -> dict[str, Any]:
	"""Get the type hints for the given object after resolving the generic types as much as possible.
	Args:
	annotation: A type annotation.
	globalns: The global namespace.
	localns: The local namespace.
	include_extras: A flag indicating whether to include the ``Annotated[T, ...]`` or not.
	type_hints: Already resolved type hints
	"""
	origin = get_origin(annotation)
	if origin is None:
	# Implies the generic types have not been specified in the annotation
	if type_hints is None: # pragma: no cover
	type_hints = get_type_hints(annotation, globalns=globalns, localns=localns, include_extras=include_extras)
	typevar_map = {p: p for p in annotation.__parameters__}
	else:
	if type_hints is None: # pragma: no cover
	type_hints = get_type_hints(origin, globalns=globalns, localns=localns, include_extras=include_extras)
	# the __parameters__ is only available on the origin itself and not the annotation
	typevar_map = dict(zip(origin.__parameters__, get_args(annotation)))
	return {n: _substitute_typevars(type_, typevar_map) for n, type_ in type_hints.items()}

I see, but fn_type_hints no longer contains the expanded type information after line 214. In the previous example, fn_type_hint = {'data': ~T, 'return': ~T}

litestar/litestar/utils/signature.py

Line 214 in ef9dbb7

fn_type_hints = get_fn_type_hints(fn, namespace=signature_namespace)

[peterschutt]

Not sure what you mean. I'm just pointing out that we have a utility that does type get_type_hints() with type var expansion.

[haryle]

Sorry, I wasn't clear. Correct me if I am wrong, but I don't think that utility method gets called in the ParsedSignature.from_fn call stack.

[peterschutt]

Obviously it was me who was unclear. I wasn't saying it did - just pointing out we have the utility you mentioned which maybe we can use. LMK how it goes.

[haryle]

Ah thank you. Should I make a PR after adding it in? Sorry I am quite new to contributing to open source project.