Today we’re going to talk about something that might sound like it belongs in a sci-fi movie: coroutines. But don’t freak out, because this is just some fancy jargon for functions with the ability to pause and resume their execution. And if you’ve ever found yourself waiting for a long-running operation to finish before moving on to other tasks, well…you might want to keep reading!
To set the stage: what exactly are coroutines? In simple terms, they’re regular functions that can be paused when encountering an operation that takes too much time. When the operation is complete, you can resume the function and continue executing its code. This allows for asynchronous programming, which means running multiple tasks at once to improve performance.
So how do we create a coroutine in Python? Easy! Just add the async keyword before your function definition:
# Creating a coroutine in Python
# A coroutine is a function that can be paused and resumed at a later time, allowing for asynchronous programming.
# This means that multiple tasks can be run at once, improving performance.
# To create a coroutine in Python, simply add the "async" keyword before the function definition.
# Define the coroutine function with the "async" keyword
async def my_coroutine():
# Some code here...
# This is where the coroutine can be paused and resumed later
# The "await" keyword is used to pause the coroutine and wait for a long running operation to complete
await long_running_operation()
# Once the operation is complete, the coroutine can be resumed and the code after the "await" statement will be executed.
# The "await" keyword is used to pause the coroutine and wait for a long running operation to complete.
# This allows for asynchronous programming, as the coroutine can be paused and other tasks can be executed while waiting for the operation to finish.
# The "async" keyword before the function definition indicates that this is a coroutine function.
# This allows the function to be paused and resumed, making it a coroutine.
# The "await" keyword can only be used within a coroutine function.
# It is used to pause the coroutine and wait for a long running operation to complete.
# The "await" keyword is followed by a function call, which is the long running operation that the coroutine is waiting for.
# This function call can be any long running operation, such as making a network request or performing a complex calculation.
# Once the operation is complete, the coroutine can be resumed and the code after the "await" statement will be executed.
# This allows for the coroutine to continue its execution and perform any necessary tasks after the long running operation is finished.
The await keyword is what allows us to pause and resume execution. When we encounter an await statement, Python will automatically yield control back to the event loop (more on that in a bit) until the operation being waited for has completed. This means other tasks can be executed while we’re waiting!
Now how coroutines work with asyncio, which is Python’s built-in library for asynchronous programming. When you run an async function using the async keyword, it returns a coroutine object that needs to be scheduled in an event loop. The event loop is responsible for managing all of our tasks and ensuring they are executed in order.
Here’s what a basic example might look like:
# Import the asyncio library to use asynchronous programming
import asyncio
# Define an async function using the async keyword
async def my_coroutine():
# Some code here...
# Use the await keyword to wait for the long_running_operation to complete
await long_running_operation()
# More code after the operation completes...
# Get the event loop to manage our tasks
loop = asyncio.get_event_loop()
# Create a list of tasks to be executed
tasks = [my_coroutine()]
# Run the event loop until all tasks are completed
loop.run_until_complete(asyncio.wait(tasks))
In this example, we’re creating a coroutine object using our my_coroutine function and scheduling it in the event loop using asyncio.wait(). The run_until_complete() method is what tells Python to keep running tasks until everything has completed or an exception occurs.
Coroutines are just regular functions with a fancy new feature: the ability to pause and resume execution. They’re perfect for asynchronous programming, which can greatly improve performance by allowing multiple tasks to be executed at once. And best of all…they don’t require any crazy sci-fi technology or time travel!