Lazy provider

docs/experimental/lazy.md

@@ -0,0 +1,52 @@
+# Lazy Provider
+
+The `LazyProvider` enables you to reference other providers without explicitly 
+importing them into your module.
+
+This can be helpful if you have a circular dependency between providers in 
+multiple containers.
+
+
+## Creating a Lazy Provider
+
+=== "Single import string"
+    ```python
+    from that_depends.experimental import LazyProvider
+
+    lazy_p = LazyProvider("full.import.string.including.attributes")
+    ```
+=== "Separate module and provider"
+    ```python
+    from that_depends.experimental import LazyProvider
+
+    lazy_p = LazyProvider(module_string="my.module", provider_string="attribute.path")
+    ```
+
+
+## Usage
+
+You can use the lazy provider in exactly the same way as you would use the referenced provider.
+
+```python
+# first_container.py
+from that_depends import BaseContainer, providers, ContextScopes
+
+def my_creator():
+    yield 42
+
+class FirstContainer(BaseContainer):
+    value_provider = providers.ContextResource(my_creator).with_config(scope=ContextScopes.APP)
+```
+
+You can lazily import this provider:
+```python
+# second_container.py
+from that_depends.experimental import LazyProvider
+from that_depends import BaseContainer, providers
+class SecondContainer(BaseContainer):
+    lazy_value = LazyProvider("first_container.FirstContainer.value_provider")
+
+
+with SecondContainer.lazy_value.context_sync(force=True):
+    SecondContainer.lazy_value.resolve_sync() # 42
+```

mkdocs.yml

@@ -23,6 +23,8 @@ nav:
       - Selector: providers/selector.md
       - Singletons: providers/singleton.md
       - State: providers/state.md
+  - Experimental Features:
+      - Lazy Provider: experimental/lazy.md
 
   - Integrations:
       - FastAPI: integrations/fastapi.md

pyproject.toml

@@ -24,7 +24,7 @@ fastapi = [
     "fastapi",
 ]
 faststream = [
-    "faststream"
+    "faststream<0.6.0"
 ]
 
 [project.urls]

tests/experimental/test_container_1.py

@@ -0,0 +1,15 @@
+from tests.experimental.test_container_2 import Container2
+from that_depends import BaseContainer, providers
+from that_depends.experimental import LazyProvider
+
+
+class Container1(BaseContainer):
+    """Test Container 1."""
+
+    alias = "container_1"
+    obj_1 = providers.Object(1)
+    obj_2 = LazyProvider(module_string="tests.experimental.test_container_2", provider_string="Container2.obj_2")
+
+
+def test_lazy_provider_resolution_sync() -> None:
+    assert Container2.obj_2.resolve_sync() == 2  # noqa: PLR2004

tests/experimental/test_container_2.py

@@ -0,0 +1,145 @@
+import random
+from collections.abc import AsyncIterator, Iterator
+
+import pytest
+import typing_extensions
+
+from that_depends import BaseContainer, ContextScopes, container_context, providers
+from that_depends.experimental import LazyProvider
+
+
+class _RandomWrapper:
+    def __init__(self) -> None:
+        self.value = random.random()
+
+    @typing_extensions.override
+    def __eq__(self, other: object) -> bool:
+        if isinstance(other, _RandomWrapper):
+            return self.value == other.value
+        return False  # pragma: nocover
+
+    def __hash__(self) -> int:
+        return 0  # pragma: nocover
+
+
+async def _async_creator() -> AsyncIterator[float]:
+    yield random.random()
+
+
+def _sync_creator() -> Iterator[_RandomWrapper]:
+    yield _RandomWrapper()
+
+
+class Container2(BaseContainer):
+    """Test Container 2."""
+
+    alias = "container_2"
+    default_scope = ContextScopes.APP
+    obj_1 = LazyProvider("tests.experimental.test_container_1.Container1.obj_1")
+    obj_2 = providers.Object(2)
+    async_context_provider = providers.ContextResource(_async_creator)
+    sync_context_provider = providers.ContextResource(_sync_creator)
+    singleton_provider = providers.Singleton(lambda: random.random())
+
+
+async def test_lazy_provider_resolution_async() -> None:
+    assert await Container2.obj_1.resolve() == 1
+
+
+def test_lazy_provider_override_sync() -> None:
+    override_value = 42
+    Container2.obj_1.override_sync(override_value)
+    assert Container2.obj_1.resolve_sync() == override_value
+    Container2.obj_1.reset_override_sync()
+    assert Container2.obj_1.resolve_sync() == 1
+
+
+async def test_lazy_provider_override_async() -> None:
+    override_value = 42
+    await Container2.obj_1.override(override_value)
+    assert await Container2.obj_1.resolve() == override_value
+    await Container2.obj_1.reset_override()
+    assert await Container2.obj_1.resolve() == 1
+
+
+def test_lazy_provider_invalid_state() -> None:
+    lazy_provider = LazyProvider(
+        module_string="tests.experimental.test_container_2", provider_string="Container2.sync_context_provider"
+    )
+    lazy_provider._module_string = None
+    with pytest.raises(RuntimeError):
+        lazy_provider.resolve_sync()
+
+
+async def test_lazy_provider_context_resource_async() -> None:
+    lazy_provider = LazyProvider("tests.experimental.test_container_2.Container2.async_context_provider")
+    async with lazy_provider.context_async(force=True):
+        assert await lazy_provider.resolve() == await Container2.async_context_provider.resolve()
+        async with Container2.async_context_provider.context_async(force=True):
+            assert await lazy_provider.resolve() == await Container2.async_context_provider.resolve()
+
+    with pytest.raises(RuntimeError):
+        await lazy_provider.resolve()
+
+    async with container_context(Container2, scope=ContextScopes.APP):
+        assert await lazy_provider.resolve() == await Container2.async_context_provider.resolve()
+
+    assert lazy_provider.get_scope() == ContextScopes.APP
+
+    assert lazy_provider.supports_context_sync() is False
+
+
+def test_lazy_provider_context_resource_sync() -> None:
+    lazy_provider = LazyProvider("tests.experimental.test_container_2.Container2.sync_context_provider")
+    with lazy_provider.context_sync(force=True):
+        assert lazy_provider.resolve_sync() == Container2.sync_context_provider.resolve_sync()
+        with Container2.sync_context_provider.context_sync(force=True):
+            assert lazy_provider.resolve_sync() == Container2.sync_context_provider.resolve_sync()
+
+    with pytest.raises(RuntimeError):
+        lazy_provider.resolve_sync()
+
+    with container_context(Container2, scope=ContextScopes.APP):
+        assert lazy_provider.resolve_sync() == Container2.sync_context_provider.resolve_sync()
+
+    assert lazy_provider.get_scope() == ContextScopes.APP
+
+    assert lazy_provider.supports_context_sync() is True
+
+
+async def test_lazy_provider_tear_down_async() -> None:
+    lazy_provider = LazyProvider("tests.experimental.test_container_2.Container2.singleton_provider")
+    assert lazy_provider.resolve_sync() == Container2.singleton_provider.resolve_sync()
+
+    await lazy_provider.tear_down()
+
+    assert await lazy_provider.resolve() == Container2.singleton_provider.resolve_sync()
+
+
+def test_lazy_provider_tear_down_sync() -> None:
+    lazy_provider = LazyProvider("tests.experimental.test_container_2.Container2.singleton_provider")
+    assert lazy_provider.resolve_sync() == Container2.singleton_provider.resolve_sync()
+
+    lazy_provider.tear_down_sync()
+
+    assert lazy_provider.resolve_sync() == Container2.singleton_provider.resolve_sync()
+
+
+async def test_lazy_provider_not_implemented() -> None:
+    lazy_provider = Container2.obj_1
+    with pytest.raises(NotImplementedError):
+        lazy_provider.get_scope()
+    with pytest.raises(NotImplementedError):
+        lazy_provider.context_sync()
+    with pytest.raises(NotImplementedError):
+        lazy_provider.context_async()
+    with pytest.raises(NotImplementedError):
+        lazy_provider.tear_down_sync()
+    with pytest.raises(NotImplementedError):
+        await lazy_provider.tear_down()
+
+
+def test_lazy_provider_attr_getter() -> None:
+    lazy_provider = LazyProvider("tests.experimental.test_container_2.Container2.sync_context_provider")
+    with lazy_provider.context_sync(force=True):
+        assert isinstance(lazy_provider.value.resolve_sync(), float)

tests/experimental/test_lazy_provider.py

@@ -0,0 +1,30 @@
+import pytest
+
+from that_depends.experimental import LazyProvider
+
+
+def test_lazy_provider_incorrect_initialization() -> None:
+    with pytest.raises(
+        ValueError,
+        match=r"You must provide either import_string "
+        "OR both module_string AND provider_string, but not both or neither.",
+    ):
+        LazyProvider(module_string="3213")  # type: ignore[call-overload]
+
+    with pytest.raises(ValueError, match=r"Invalid import_string ''"):
+        LazyProvider("")
+
+    with pytest.raises(ValueError, match=r"Invalid provider_string ''"):
+        LazyProvider(module_string="some.module", provider_string="")
+
+    with pytest.raises(ValueError, match=r"Invalid module_string '.'"):
+        LazyProvider(module_string=".", provider_string="SomeProvider")
+
+    with pytest.raises(ValueError, match=r"Invalid import_string 'import.'"):
+        LazyProvider("import.")
+
+
+def test_lazy_provider_incorrect_import_string() -> None:
+    p = LazyProvider("some.random.path")
+    with pytest.raises(ImportError):
+        p.resolve_sync()

that_depends/experimental/__init__.py

@@ -0,0 +1,8 @@
+"""Experimental features."""
+
+from that_depends.experimental.providers import LazyProvider
+
+
+__all__ = [
+    "LazyProvider",
+]