# Factories

Factories are initialized on every call.

## Factory

- Class or simple function is allowed.

  ```python
  import dataclasses

  from that_depends import BaseContainer, providers


  @dataclasses.dataclass(kw_only=True, slots=True)
  class IndependentFactory:
      dep1: str
      dep2: int


  class DIContainer(BaseContainer):
      independent_factory = providers.Factory(IndependentFactory, dep1="text", dep2=123)
  ```

## AsyncFactory

- Allows both sync and async creators.

- Can only be resolved asynchronously, even if the creator is sync.

  ```python
  import datetime

  from that_depends import BaseContainer, providers


  async def async_factory() -> datetime.datetime:
      return datetime.datetime.now(tz=datetime.timezone.utc)


  class DIContainer(BaseContainer):
      async_factory = providers.AsyncFactory(async_factory)
  ```

> Note: If you have a class that has dependencies which need to be resolved asynchronously, you can use `AsyncFactory` to create instances of that class. The factory will handle the async resolution of dependencies.

## Retrieving provider as a Callable

When you use a factory‑based provider such as `Factory` (for sync logic) or `AsyncFactory` (for async logic), the resulting provider instance has two special properties:

- **`.provider`** — returns an *async callable* that, when awaited, resolves the resource.
- **`.provider_sync`** — returns a *sync callable* that, when called, resolves the resource.

You can think of these as no-argument functions that produce the resource you defined—similar to calling `resolve()` or `resolve_sync()` directly, but in a more convenient form when you want a standalone function handle.

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### Basic Usage

#### Defining Providers in a Container

Suppose you have a `BaseContainer` subclass that defines both a sync and an async resource:

```python
from that_depends import BaseContainer
from that_depends.providers import Factory, AsyncFactory

def build_sync_message() -> str:
    return "Hello from sync provider!"

async def build_async_message() -> str:
    # Possibly perform async setup, I/O, etc.
    return "Hello from async provider!"

class MyContainer(BaseContainer):
    # Synchronous Factory
    sync_message = Factory(build_sync_message)

    # Asynchronous Factory
    async_message = AsyncFactory(build_async_message)
```

Here, `sync_message` is a `Factory` which calls a plain function, while `async_message` is an `AsyncFactory` which calls an async function.

______________________________________________________________________

#### Resolving Resources via `.provider` and `.provider_sync`

The `.provider` property gives you an *async function* to await, and `.provider_sync` gives you a *synchronous* callable. They effectively wrap `.resolve()` and `.resolve_sync()`.

**Synchronous Resolution**

```python
# In a synchronous function or interactive session
>>> msg = MyContainer.sync_message.provider_sync
>>> print(msg)
Hello from sync provider!
```

Here, `provider_sync` is a no-argument function that immediately returns the resolved value.

**Asynchronous Resolution**

```python
import asyncio

async def main():
    # Acquire the async resource by awaiting the provider property
    msg = await MyContainer.async_message.provider
    print(msg)

asyncio.run(main())
```

Within an async function, `MyContainer.async_message.provider` gives a no-argument async function to `await`.

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### Passing the Provider Function Around

Sometimes you may want to store or pass around the provider function itself (rather than resolving it immediately):

```python
class AnotherClass:
    def __init__(self, sync_factory_callable: callable):
        self._factory_callable = sync_factory_callable

    def get_message(self) -> str:
        return self._factory_callable()


# Passing MyContainer.sync_message.sync_provider to AnotherClass
provider_callable = MyContainer.sync_message.provider_sync
another_instance = AnotherClass(provider_callable)
print(another_instance.get_message())  # "Hello from sync provider!"
```

Because `.provider_sync` is just a callable returning your dependency, it can be shared easily throughout your code.

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### Example: Using Factories with Parameters

`Factory` and `AsyncFactory` can accept dependencies (including other providers) as parameters:

```python
def greet(name: str) -> str:
    return f"Hello, {name}!"

class MyContainer(BaseContainer):
    name = Factory(lambda: "Alice")
    greeting = Factory(greet, name)
```

```python
>>> greeting_sync_fn = MyContainer.greeting.provider_sync
>>> print(greeting_sync_fn())
Hello, Alice!
```

Under the hood, `greeting` calls `greet` with the result of `name.resolve_sync()`.

______________________________________________________________________

### Context Considerations

If your providers use `ContextResource` or require a named scope (for instance, `REQUEST`), you need to wrap your resolves in a context manager:

```python
from that_depends.providers import container_context, ContextScopes


class ContextfulContainer(BaseContainer):
    default_scope = ContextScopes.REQUEST
    # ... define context-based providers ...


with container_context(ContextfulContainer, scope=ContextScopes.REQUEST):
    result = ContextfulContainer.some_resource.provider_sync()
    # ...
```

You still call `.provider_sync` or `.provider`, but the container or context usage ensures resources are valid within the required scope.

This pattern simplifies passing creation logic around in your code, preserving testability and clarity—whether you need sync or async behavior.