Provider activation

src/dishka/__init__.py

@@ -1,6 +1,8 @@
 __all__ = [
     "DEFAULT_COMPONENT",
     "STRICT_VALIDATION",
+    "ActivationContext",
+    "Activator",
     "AnyOf",
     "AsyncContainer",
     "BaseScope",
@@ -9,6 +11,7 @@
     "DependencyKey",
     "FromComponent",
     "FromDishka",
+    "Has",
     "Provider",
     "Scope",
     "ValidationSettings",
@@ -25,6 +28,7 @@
 
 from .async_container import AsyncContainer, make_async_container
 from .container import Container, make_container
+from .entities.activator import ActivationContext, Activator, Has
 from .entities.component import DEFAULT_COMPONENT, Component
 from .entities.depends_marker import FromDishka
 from .entities.key import DependencyKey, FromComponent

src/dishka/async_container.py

@@ -275,6 +275,7 @@ def make_async_container(
         providers=(*providers, context_provider),
         skip_validation=skip_validation,
         validation_settings=validation_settings,
+        root_context=context,
     ).build()
     container = AsyncContainer(
         *registries,

src/dishka/container.py

@@ -272,6 +272,7 @@ def make_container(
         providers=(*providers, context_provider),
         skip_validation=skip_validation,
         validation_settings=validation_settings,
+        root_context=context,
     ).build()
     container = Container(
         *registries,

src/dishka/dependency_source/alias.py

@@ -2,6 +2,7 @@
 
 from typing import Any
 
+from dishka.entities.activator import Activator
 from dishka.entities.component import Component
 from dishka.entities.factory_type import FactoryType
 from dishka.entities.key import DependencyKey
@@ -14,19 +15,24 @@ def _identity(x: Any) -> Any:
 
 
 class Alias:
-    __slots__ = ("cache", "component", "override", "provides", "source")
+    __slots__ = (
+        "cache", "component", "override",
+        "provides", "source", "when",
+    )
 
     def __init__(
             self, *,
             source: DependencyKey,
             provides: DependencyKey,
             cache: bool,
             override: bool,
+            when: Activator | None,
     ) -> None:
         self.source = source
         self.provides = provides
         self.cache = cache
         self.override = override
+        self.when = when
 
     def as_factory(
             self, scope: BaseScope | None, component: Component | None,
@@ -41,6 +47,7 @@ def as_factory(
             type_=FactoryType.ALIAS,
             cache=self.cache,
             override=self.override,
+            when=self.when,
         )
 
     def __get__(self, instance: Any, owner: Any) -> Alias:

src/dishka/dependency_source/context_var.py

@@ -2,6 +2,7 @@
 
 from typing import Any, NoReturn
 
+from dishka.entities.activator import Activator
 from dishka.entities.component import DEFAULT_COMPONENT, Component
 from dishka.entities.factory_type import FactoryType
 from dishka.entities.key import DependencyKey
@@ -15,21 +16,21 @@ def context_stub() -> NoReturn:
 
 
 class ContextVariable:
-    __slots__ = ("override", "provides", "scope")
+    __slots__ = ("override", "provides", "scope", "when")
 
     def __init__(
             self, *,
             provides: DependencyKey,
             scope: BaseScope | None,
             override: bool,
+            when: Activator | None,
     ) -> None:
         self.provides = provides
         self.scope = scope
         self.override = override
+        self.when = when
 
-    def as_factory(
-            self, component: Component,
-    ) -> Factory:
+    def as_factory(self, component: Component | None) -> Factory:
         if component == DEFAULT_COMPONENT:
             return Factory(
                 scope=self.scope,
@@ -41,6 +42,7 @@ def as_factory(
                 type_=FactoryType.CONTEXT,
                 cache=False,
                 override=self.override,
+                when=self.when,
             )
         else:
             aliased = Alias(
@@ -51,6 +53,7 @@ def as_factory(
                     component=component,
                     type_hint=self.provides.type_hint,
                 ),
+                when=self.when,
             )
             return aliased.as_factory(scope=self.scope, component=component)
 
@@ -60,4 +63,5 @@ def __get__(self, instance: Any, owner: Any) -> ContextVariable:
             scope=scope,
             provides=self.provides,
             override=self.override,
+            when=self.when,
         )

src/dishka/dependency_source/decorator.py

@@ -2,6 +2,7 @@
 
 from typing import Any, TypeVar, get_args, get_origin
 
+from dishka.entities.activator import Activator
 from dishka.entities.component import Component
 from dishka.entities.key import DependencyKey
 from dishka.entities.scope import BaseScope
@@ -10,20 +11,22 @@
 
 
 class Decorator:
-    __slots__ = ("factory", "provides", "scope")
+    __slots__ = ("factory", "provides", "scope", "when")
 
     def __init__(
             self,
             factory: Factory,
             provides: DependencyKey | None = None,
             scope: BaseScope | None = None,
+            when: Activator | None = None,
     ) -> None:
         self.factory = factory
         if provides:
             self.provides = provides
         else:
             self.provides = factory.provides
         self.scope = scope
+        self.when = when
 
     def is_generic(self) -> bool:
         return (
@@ -39,7 +42,7 @@ def as_factory(
             scope: BaseScope,
             new_dependency: DependencyKey,
             cache: bool,
-            component: Component,
+            component: Component | None,
     ) -> Factory:
         typevar_replacement = get_typevar_replacement(
             self.provides.type_hint,
@@ -67,6 +70,7 @@ def as_factory(
             type_=self.factory.type,
             cache=cache,
             override=False,
+            when=self.when,
         )
 
     def _replace_dep(
@@ -95,4 +99,5 @@ def __get__(self, instance: Any, owner: Any) -> Decorator:
         return Decorator(
             self.factory.__get__(instance, owner),
             scope=self.scope,
+            when=self.when,
         )

src/dishka/dependency_source/factory.py

@@ -6,6 +6,7 @@
 )
 from typing import Any
 
+from dishka.entities.activator import Activator
 from dishka.entities.component import Component
 from dishka.entities.factory_type import FactoryData, FactoryType
 from dishka.entities.key import DependencyKey
@@ -19,6 +20,7 @@ class Factory(FactoryData):
         "is_to_bind",
         "kw_dependencies",
         "override",
+        "when",
     )
 
     def __init__(
@@ -33,6 +35,7 @@ def __init__(
             is_to_bind: bool,
             cache: bool,
             override: bool,
+            when: Activator | None,
     ) -> None:
         super().__init__(
             source=source,
@@ -45,6 +48,7 @@ def __init__(
         self.is_to_bind = is_to_bind
         self.cache = cache
         self.override = override
+        self.when = when
 
     def __get__(self, instance: Any, owner: Any) -> Factory:
         scope = self.scope or instance.scope
@@ -66,9 +70,10 @@ def __get__(self, instance: Any, owner: Any) -> Factory:
             is_to_bind=False,
             cache=self.cache,
             override=self.override,
+            when=self.when,
         )
 
-    def with_component(self, component: Component) -> Factory:
+    def with_component(self, component: Component | None) -> Factory:
         return Factory(
             dependencies=[
                 d.with_component(component) for d in self.dependencies
@@ -84,4 +89,5 @@ def with_component(self, component: Component) -> Factory:
             cache=self.cache,
             type_=self.type,
             override=self.override,
+            when=self.when,
         )

src/dishka/entities/activator.py

@@ -0,0 +1,43 @@
+from abc import abstractmethod
+from collections.abc import Callable
+from typing import Any, NamedTuple, Protocol, TypeAlias
+
+from dishka.entities.component import Component
+from dishka.entities.key import DependencyKey
+
+
+class ActivationBuilder(Protocol):
+    @abstractmethod
+    def has_active(
+        self,
+        key: DependencyKey,
+        request_stack: list[DependencyKey],
+    ) -> bool:
+        raise NotImplementedError
+
+
+class ActivationContext(NamedTuple):
+    container_context: dict[Any, Any] | None
+    container_key: DependencyKey
+    key: DependencyKey
+    builder: ActivationBuilder
+    request_stack: list[DependencyKey]
+
+
+Activator: TypeAlias = Callable[[ActivationContext], bool]
+
+
+class Has:
+    def __init__(
+        self,
+        cls: Any,
+        *,
+        component: Component | None = None,
+    ) -> None:
+        self.key = DependencyKey(cls, component=component)
+
+    def __call__(self, ctx: ActivationContext) -> bool:
+        key = self.key.with_component(ctx.key.component)
+        if key in ctx.request_stack:  # cycle
+            return True
+        return ctx.builder.has_active(key, ctx.request_stack)

src/dishka/provider/base_provider.py

@@ -4,22 +4,37 @@
     Decorator,
     Factory,
 )
+from dishka.entities.activator import Activator
 from dishka.entities.component import Component
 
 
 class BaseProvider:
-    def __init__(self, component: Component | None) -> None:
+    when: Activator | None = None
+    component: Component | None = None
+
+    def __init__(
+        self,
+        component: Component | None,
+        when: Activator | None = None,
+    ) -> None:
         if component is not None:
             self.component = component
+        if when is not None:
+            self.when = when
         self.factories: list[Factory] = []
         self.aliases: list[Alias] = []
         self.decorators: list[Decorator] = []
         self.context_vars: list[ContextVariable] = []
 
 
 class ProviderWrapper(BaseProvider):
-    def __init__(self, component: Component, provider: BaseProvider) -> None:
-        super().__init__(component)
+    def __init__(
+        self,
+        component: Component,
+        provider: BaseProvider,
+        when: Activator | None = None,
+    ) -> None:
+        super().__init__(component, when=when)
         self.factories.extend(provider.factories)
         self.aliases.extend(provider.aliases)
         self.decorators.extend(provider.decorators)

src/dishka/provider/make_alias.py

@@ -5,6 +5,7 @@
     CompositeDependencySource,
     ensure_composite,
 )
+from dishka.entities.activator import Activator
 from dishka.entities.component import Component
 from dishka.entities.key import hint_to_dependency_key
 from .unpack_provides import unpack_alias
@@ -17,6 +18,7 @@ def alias(
         cache: bool = True,
         component: Component | None = None,
         override: bool = False,
+        when: Activator | None = None,
 ) -> CompositeDependencySource:
     if component is provides is None:
         raise ValueError(  # noqa: TRY003
@@ -31,6 +33,7 @@ def alias(
         provides=hint_to_dependency_key(provides),
         cache=cache,
         override=override,
+        when=when,
     )
     composite.dependency_sources.extend(unpack_alias(alias_instance))
     return composite

src/dishka/provider/make_context_var.py

@@ -6,6 +6,7 @@
     ContextVariable,
     context_stub,
 )
+from dishka.entities.activator import Activator
 from dishka.entities.component import DEFAULT_COMPONENT
 from dishka.entities.key import DependencyKey
 from dishka.entities.scope import BaseScope
@@ -20,6 +21,7 @@ def from_context(
         *,
         scope: BaseScope | None = None,
         override: bool = False,
+        when: Activator | None = None,
 ) -> CompositeDependencySource:
     composite = CompositeDependencySource(origin=context_stub)
     composite.dependency_sources.append(
@@ -30,6 +32,7 @@ def from_context(
                 type_hint=provides,
                 component=DEFAULT_COMPONENT,
             ),
+            when=when,
         ),
     )
 
@@ -41,6 +44,7 @@ def from_context(
                 provides=DependencyKey(base_type, DEFAULT_COMPONENT),
                 cache=True,
                 override=override,
+                when=when,
             ),
         )
     return composite