What is the typing.Unpack?

Question

Accepted Answer

**Unpack** allows **TypedDict** values to be unpacked as keyword arguments.

```python
from typing import TypedDict, Unpack

class Options(TypedDict, total=False):
    timeout: int
    retries: int
    headers: dict[str, str]

def fetch(url: str, **kwargs: Unpack[Options]) -> str:
    timeout = kwargs.get("timeout", 30)
    retries = kwargs.get("retries", 3)
    return f"Fetching {url} with timeout={timeout}"

# Type-safe keyword arguments
fetch("http://example.com", timeout=10, retries=5)  # OK
# fetch("http://example.com", invalid="param")  # Type error!

# With FastAPI
from fastapi import FastAPI

app = FastAPI()

class QueryParams(TypedDict, total=False):
    skip: int
    limit: int
    search: str

@app.get("/items/")
async def get_items(**params: Unpack[QueryParams]):
    skip = params.get("skip", 0)
    limit = params.get("limit", 10)
    return {"skip": skip, "limit": limit}
```

**Benefits:**
- Type-safe **kwargs.
- IDE autocompletion.
- Clear function signatures.

Python: What is the typing.Unpack?