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Make inject markers for Annotations public #269

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Make inject markers for Annotations public #269

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29 changes: 18 additions & 11 deletions injector/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -98,15 +98,15 @@ def wrapper(*args: Any, **kwargs: Any) -> Any:
lock = threading.RLock()


_inject_marker = object()
_noinject_marker = object()
inject_marker = object()
noinject_marker = object()

InjectT = TypeVar('InjectT')
Inject = Annotated[InjectT, _inject_marker]
Inject = Annotated[InjectT, inject_marker]
"""An experimental way to declare injectable dependencies utilizing a `PEP 593`_ implementation
in Python 3.9 and backported to Python 3.7+ in `typing_extensions`.

Those two declarations are equivalent::
These three declarations are equivalent::

@inject
def fun(t: SomeType) -> None:
Expand All @@ -115,8 +115,11 @@ def fun(t: SomeType) -> None:
def fun(t: Inject[SomeType]) -> None:
pass

def fun(t: Annotated[SomeType, inject_marker]) -> None:
pass

The advantage over using :func:`inject` is that if you have some noninjectable parameters
it may be easier to spot what are they. Those two are equivalent::
it may be easier to spot what are they. These two are equivalent::

@inject
@noninjectable('s')
Expand All @@ -142,7 +145,7 @@ def fun(t: Inject[SomeType], s: SomeOtherType) -> None:
.. _typing_extensions: https://pypi.org/project/typing-extensions/
"""

NoInject = Annotated[InjectT, _noinject_marker]
NoInject = Annotated[InjectT, noinject_marker]
"""An experimental way to declare noninjectable dependencies utilizing a `PEP 593`_ implementation
in Python 3.9 and backported to Python 3.7+ in `typing_extensions`.

Expand All @@ -154,7 +157,7 @@ def fun(t: Inject[SomeType], s: SomeOtherType) -> None:
* The declaration may be relatively distance in space from the actual parameter declaration, thus
hindering readability

`NoInject` solves both of those concerns, for example (those two declarations are equivalent)::
`NoInject` solves both of those concerns, for example (these three declarations are equivalent)::

@inject
@noninjectable('b')
Expand All @@ -165,6 +168,10 @@ def fun(a: TypeA, b: TypeB) -> None:
def fun(a: TypeA, b: NoInject[TypeB]) -> None:
pass

@inject
def fun(a: TypeA, b: Annotated[TypeB, noinject_marker]) -> None:
pass

.. seealso::

Function :func:`get_bindings`
Expand Down Expand Up @@ -1166,7 +1173,7 @@ def get_bindings(callable: Callable) -> Dict[str, type]:
if not hasattr(callable, '__bindings__'):
type_hints = get_type_hints(callable, include_extras=True)
has_injectable_parameters = any(
_is_specialization(v, Annotated) and _inject_marker in v.__metadata__ for v in type_hints.values()
_is_specialization(v, Annotated) and inject_marker in v.__metadata__ for v in type_hints.values()
)

if not has_injectable_parameters:
Expand Down Expand Up @@ -1244,7 +1251,7 @@ def _is_new_union_type(instance: Any) -> bool:
else:
metadata = tuple()

if only_explicit_bindings and _inject_marker not in metadata or _noinject_marker in metadata:
if only_explicit_bindings and inject_marker not in metadata or noinject_marker in metadata:
del bindings[k]
elif _is_specialization(v, Union) or _is_new_union_type(v):
# We don't treat Optional parameters in any special way at the moment.
Expand All @@ -1264,8 +1271,8 @@ def _is_new_union_type(instance: Any) -> bool:
}
if (
only_explicit_bindings
and _inject_marker not in union_metadata
or _noinject_marker in union_metadata
and inject_marker not in union_metadata
or noinject_marker in union_metadata
):
del bindings[k]
else:
Expand Down