flake8-escaping-style

A flake8 plugin to help maintain a consistent style of escape sequences in string and bytes literals throughout your project.

Installation

This plugin requires at least version 3.7 of Python.

Like most flake8 plugins, start by installing the package:

pip install flake8-escaping-style

Then in your flake8 configuration, use a combination of select and ignore that matches your preferences.

For example, here's how it would look like if you wanted to prevent all escapes except for \N{name of character}:

select=ESC1
ignore=ESC105

List of error codes

For string literals (str)

For byte string literals (bytes)

For completeness's sake, this plugin can also detect escape styles in bytestring literals:

Motivation

Python has several different ways to write escape sequences.

In the old days of Python 2, any file was assumed to be ascii encoded unless you added a special comment on the first line. That meant that if you wanted to write the string "café" in your source code, you had to either add that comment on the first line of your file, or use an escape sequence like "caf\xe9" or "caf\u00E9".

Nowadays, Python has lifted those limitations and uses a more practical default encoding (utf-8, see PEP3120). So for most string literals you can use the character you want without having to use escape sequences at all.

I'd still recommend using an escape sequence when using "weird" ¹ characters and especially invisible ones. But in that case I like to use the "named character" escaping style \N{name}.

Consider for example the case of a non-breaking space. It's a nifty little character and it can be very useful sometimes but it can also lead to some tough debugging:

Can you spot the difference?

>>> "hello world" == "hello world"
False

Using an escape sequence here (rather than the character itself) makes it more obvious as to what is going on:

>>> "hello world" == "hello\xa0world"
False

That's better in my opinion, but it still requires knowing which character has the number A0 in hexadecimal. The best option is to use a named escape sequence:

>>> "hello world" == "hello\N{no-break space}world"
False

For that reason, I prefer my projects to only use the "named" style of escape sequences (ESC105).