What are send() and throw() methods on generators?

Question

Accepted Answer

Generators can **receive values** with `send()` and **handle exceptions** with `throw()`.

**send() — pass values into generator:**
```python
def accumulator():
    total = 0
    while True:
        value = yield total
        if value is None:
            break
        total += value

gen = accumulator()
next(gen)          # Initialize (first yield)
gen.send(10)       # total = 10, yields 10
gen.send(20)       # total = 30, yields 30
gen.send(5)        # total = 35, yields 35
```

**throw() — inject exceptions:**
```python
def resilient():
    while True:
        try:
            value = yield
            print(f"Got: {value}")
        except ValueError:
            print("Invalid value, retrying")

gen = resilient()
next(gen)
gen.send("hello")  # Got: hello
gen.throw(ValueError, "bad input")
# Invalid value, retrying
```

**close()** — stops generator, triggers GeneratorExit.

Python: What are send() and throw() methods on generators?