What is the walrus operator (:=)?

Question

Accepted Answer

**Walrus operator (:=)** — assignment **inside an expression** (Python 3.8+).

```python
# Without walrus
data = get_data()
if data:
    process(data)

# With walrus
if data := get_data():
    process(data)

# In loop
while chunk := file.read(1024):
    process(chunk)

# In list comprehension
results = [y for x in data if (y := expensive(x)) > 0]

# In condition
if (n := len(items)) > 10:
    print(f"Too many items: {n}")

# With regex
import re
if match := re.search(r"\d+", "abc123def"):
    print(match.group())  # "123"
```

**Advantages:**
- Fewer lines.
- Avoid repeated computation.
- More readable code.

Python: What is the walrus operator (:=)?