Python aiter() Function

The aiter() function in Python is used to get an asynchronous iterator from an asynchronous iterable. It is especially useful when working with async for loops and asynchronous generators.

Syntax

aiter(async_iterable)

Parameters:

• async_iterable – An object that supports asynchronous iteration (must implement __aiter__()).

Returns:

• An asynchronous iterator that can be used in an async for loop.

Example: Using aiter() with Async Generator

import asyncio

class AsyncCounter:
    def __init__(self, limit):
        self.limit = limit

    def __aiter__(self):
        self.count = 0
        return self

    async def __anext__(self):
        if self.count < self.limit:
            self.count += 1
            return self.count
        else:
            raise StopAsyncIteration

async def main():
    async_iter = aiter(AsyncCounter(3))
    async for num in async_iter:
        print(num)

asyncio.run(main())

1
2
3

When to Use aiter()?

• When you want to manually get an async iterator (e.g., to pass into other async functions).
• In advanced async programming, when integrating async iteration into custom classes.

Common Mistake

• Using aiter() on a regular iterable like a list will raise a TypeError.
• It only works with objects that define an asynchronous iterator using __aiter__() and __anext__().

Interview Tip

If you’re working on async I/O or streaming data, aiter() can be used to create pipelines that process data asynchronously.

Summary

• aiter() returns an asynchronous iterator.
• It’s used only with async iterables in async for loops.
• It requires the object to define __aiter__() and __anext__().

Practice Problem

Create an asynchronous class that yields even numbers from 2 to 10 using aiter().