How can I split up a long f-string in Python?

Question

I am getting a line too long PEP 8 E501 issue.

f'Leave Request created successfully. Approvers sent the request for approval: {leave_approver_list}'

I tried using a multi-line string, but that brings in a \n, which breaks my test:

f'''Leave Request created successfully.
Approvers sent the request for approval: {leave_approver_list}'''

How can I keep it single line and pass PEP 8 linting?

This is indeed a partial duplicate, but the duplicate does not pertain to f strings, a _slight_ modification is needed to that answer. — cs95, Feb 20 '18 at 08:58

score 121 · Accepted Answer · answered Feb 20 '18 at 09:05

121

msg = (
         f'Leave Request created successfully. '
         f'Approvers sent the request for approval: {leave_approver_list}'
)

Note, the first literal doesn't need an f, but I include it for consistency/readability.

answered Feb 20 '18 at 09:05

11

To add to that: [_"The preferred way of wrapping long lines is by using Python's implied line continuation inside parentheses, brackets and braces. Long lines can be broken over multiple lines by wrapping expressions in parentheses. These should be used in preference to using a backslash for line continuation."_](https://www.python.org/dev/peps/pep-0008/#maximum-line-length) – moooeeeep Feb 20 '18 at 09:15
The first line should not have an `f` – Aidan H Apr 09 '21 at 18:19
6

@AidanH why *should* it not? It makes no difference, so it comes down to a style choice. I prefer the `f` here so they line up. I can understand why people would feel otherwise, though. I actually *noted* this in the answer. – juanpa.arrivillaga Apr 09 '21 at 18:32

score 17 · Answer 2 · edited Apr 27 '22 at 12:46

17

You will need a line break unless you wrap your string within parentheses. In this case, f will need to be prepended to the second line:

'Leave Request created successfully.'\
f'Approvers sent the request for approval: {leave_approver_list}'

Here's a little demo:

In [97]: a = 123

In [98]: 'foo_'\
    ...: f'bar_{a}'
Out[98]: 'foo_bar_123'

I recommend juanpa's answer since it is cleaner, but this is one way to do this.

edited Apr 27 '22 at 12:46

Peter Mortensen

answered Feb 20 '18 at 08:59

cs95

2

"But f will need to be prepended to the second line"- why? – Chris_Rands Feb 20 '18 at 09:06
1

@Chris_Rands Otherwise, the second line is treated as a literal string, and the variable is not substituted in. – cs95 Feb 20 '18 at 09:07
In your answer, you have a multiline string, so it is not required. – cs95 Feb 20 '18 at 09:07

2 Answers2