Use Python f-strings and never look back!

❓Are you using f-strings to format your strings in Python? Yes? Great.
🚀 If not, consider dropping your tired old format approach and get with the new(ish) stuff: f-strings.
📚 There's plenty of blogs out there that tell you all about f-strings. They tell you at length about the old approaches, % formatting and .format(), so I'm not going to go over all that, I'm just here to encourage you to take a look at f-strings.
🤔 Why? I'm using f-strings all the time now, and .format() seems clunky and overly verbose in comparison.

Here's the basics:

• f-strings is the name given to 'formatted string literals'
• Python 3.6+
• Similar in approach to .format() but less verbose, which helps keep your line length down and improve code readability.

A few examples

Here's a simple combination of string variable declaration and print using .format():

>>> device = "clocks"
>>> time = "thirteen"
>>> sentence = "The {} were striking {}".format(device, time)
>>> print(sentence)
The clocks were striking thirteen

Now, the same code, but using f-string:

>>> device = "clocks"
>>> time = "thirteen"
>>> sentence = f"The {device} were striking {time}"
>>> print(sentence)
The clocks were striking thirteen

Looking at the two approaches it doesn't seem like much of a difference. But I think the improvement are enough to make me switch to f-strings and never look back.

• F-strings save you eight characters by using a single 'f' to declare that the code uses f-strings, rather than the '.format()'.
• Writing code is more intuitive, I feel, adding the string variables within the string itself, rather than saving this for the end of the line.
• Reading code is easier because the declarations are right there in the string, again, rather than at the end of the line.
• N.B. .format does allow variables in the braces, but that has the additional requirement of having to declare those in the final brackets, like so:

sentence = "The {device} were striking {time}".format(
device=device, time=time
)

As you can see, this approach is even more verbose.

In isolation, all this points may seem minor, but as string formatting is such a necessary part of so much Python code, these small improvements can make a big difference to the overall experience of reading and writing Python.

Some extra details

Quotation marks can be used within an f-string, as long as different types are used

>>> f'{"quoted string"}'
'quoted string'

Methods can be called directly

>>> sentence = f"The {device.upper()} were striking {time}"
>>> print(sentence)
The CLOCKS were striking thirteen

For more details, check out PEP 498, the proposal that was developed into f-strings here.

Give f-strings a go, I hope you find them as useful as I have.

Thanks for reading.

🐦 @joeneville_