What is functools.wraps and why is it important?

Question

Accepted Answer

**functools.wraps** preserves the **original function metadata** when creating decorators.

```python
import functools

# Without wraps — metadata lost
def bad_decorator(func):
    def wrapper(*args, **kwargs):
        return func(*args, **kwargs)
    return wrapper

# With wraps — metadata preserved
@functools.wraps(func)
def good_decorator(func):
    def wrapper(*args, **kwargs):
        return func(*args, **kwargs)
    return wrapper

@bad_decorator
def my_func():
    """My docstring."""
    pass

print(my_func.__name__)  # "wrapper" (wrong!)
print(my_func.__doc__)   # None (lost!)

@good_decorator
def my_func():
    """My docstring."""
    pass

print(my_func.__name__)  # "my_func" (correct!)
print(my_func.__doc__)   # "My docstring." (preserved!)
```

**Preserved attributes:**
- `__name__` — function name.
- `__doc__` — docstring.
- `__module__` — module name.
- `__wrapped__` — original function.

**Always use `@functools.wraps(func)`** in decorators.

Python: What is functools.wraps and why is it important?