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Mike Driscoll

7 Nov, 10 tweets, 5 min read

#Python 3 has had asynchronous capabilities since 3.4. So let's talk about that today!

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Your first stop when learning about async in #Python is the official documentation.

There you will learn about the following:

🐍 The `asyncio` module
🐍 The `async` and `await` keywords

docs.python.org/3/library/asyn…

The #Python documentation has a nice "Hello World" example for async.

In this example, you see how to create an asynchronous function, sleep and print out some strings:

Just for fun, here's an example of what asynchronous functions looked like back in #Python 3.4

They were explicitly called coroutines and used a decorator rather than the `async def` keywords:

I attempted to learn how to use async calls with #Python a few years ago. Here is an example of scheduling calls to functions using async using the `call_soon()` method.

`call_soon()` calls your function "as soon as it can" using a FIFO queue

@mousevspython

The asyncio example in the previous tweet comes from one of my articles @mousevspython here:

blog.pythonlibrary.org/2016/07/26/pyt…

There are several other asynchronous frameworks that you can use in #Python

One popular package is Trio:

github.com/python-trio/tr…

Before async was brought to the #Python core language, the best way to do it was to use the Twisted package:

twistedmatrix.com/trac/

@dabeaz

Another popular #Python async package is Curio from @dabeaz

Check it out sometime:

github.com/dabeaz/curio

I hope you enjoyed learning a little about async in #Python.

Follow me to learn more about Python!

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More from @driscollis

Mike Driscoll

@driscollis

8 Nov

Did you know you can watermark images with #Python?

Find out how using the #Pillow package in this mini-thread!

🧵🐍👇

If you want to add text, such as a URL, to an image, you can do that pretty easily with #Python and #pillow

The following code snippet is only 21 lines!

Here are the before and after photos of the Yequina lighthouse showing how to add a watermark with #Python

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Mike Driscoll

@driscollis

8 Nov

Let's take some time and learn about testing in #Python today.

To kick things off, you'll learn about the `doctest` module!

🧵🐍👇

What is `doctest`? #Python's `doctest` modules looks for pieces of text in docstrings that look like REPL sessions.

Next, it executes them and verifies that the output in the docstring matches when the code is actually run

Check out the docs: docs.python.org/3/library/doct…

Here is an example of a #Python function with a docstring that could be used by the `doctest` module to test that function:

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Mike Driscoll

@driscollis

8 Nov

Have you ever needed to kill ☠️ a subprocess in #Python?

Let's talk a little about that a little!

🧵🐍👇

I had a use-case where I would spin up a process using `subprocess` that I wanted to kill if it ran too long

One way to do that is to use #Python's `threading` module, which has a handy `Timer` class

In this example, the `Timer` class is set to die after 5 seconds

#Python's `subprocess` module has a `run()` function that includes a `timeout` parameter (starting in 3.5) that you can use as well.

Here's an example of how that would work:

Read 5 tweets

Mike Driscoll

@driscollis

7 Oct

I use a lot of #Python resource. Here are some of my favorite!

Yes, it's another thread!

🧵👇🐍

Mouse vs Python, which is my own blog, is a resource I use myself because I write it for my future self as well as for you.

I put what I am currently working on or neat code snippets on there that I think I will use

blog.pythonlibrary.org

@doughellmann

If I need to know about a specific module in #Python, I still check the Python Module of the Week website by @doughellmann

pymotw.com/3/

Read 11 tweets

Mike Driscoll

@driscollis

7 Oct

Concurrency is a hard topic. So today we're going to talk about multiprocessing in #Python

Join for me another fun mini-thread!

🧵👇🐍

The Pros of using `multiprocessing` in #Python (part 1 of 2)

🐍 Processes use separate memory space
🐍 Code can be more straightforward compared to threads
🐍 Uses multiple CPUs / cores
🐍 Avoids the Global Interpreter Lock (GIL)

The Pros of using `multiprocessing` in #Python (part 2 of 2)

🐍 Child processes can be killed (unlike threads)
🐍 The multiprocessing module has an interface similar to `threading.Thread`
🐍 Good for CPU-bound processing (encryption, binary search, matrix multiplication)

Read 9 tweets

Mike Driscoll

@driscollis

7 Oct

Do you know how to make a #Python class method act like an attribute?

You can do that by turning the method into a `property`

Learn how in this thread!

🧵👇🐍

The first step is to look at a regular #Python class.

The following `Person` class has a method called `full_name()`. To get the full name of the `Person`, you must call `full_name()`

Wouldn't it be nice if you could just use dot notation instead of calling it?

@property

In #Python, you can turn the method into a `property` using the `@property` decorator

Once you do that, you can then use dot notation to access the `full_name()` method as if it were an instance attribute!

Read 10 tweets

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