PEP8 E128: can't figure out why a line is being flagged

Question

I'm using Sublime + Anaconda which has a built-in PyLint feature.

I can't figure out why the pars_f_name) line in the following block:

            else:
                # Get parameters file name from path.
                pars_f_name = pars_f_path.split('/')[-1]
                print ("  WARNING: Unknown '{}' ID found in line {}\n"
                       "  of '{}' file.\n").format(reader[0], l + 1,
                       pars_f_name)

# Pack params in lists.
pl_params = [flag_make_plot, plot_frmt, plot_dpi]

is being flagged as:

[W] PEP 8 (E128): continuation line under-indented for visual indent

I've tried every indentation I could think of (as suggested here) but Anaconda keeps flagging that line as a PEP8 E128 warning.

What am I doing wrong here?

Martijn Pieters · Accepted Answer · 2015-05-17T03:07:19.040

8

You need to further indent the str.format() arguments:

print ("  WARNING: Unknown '{}' ID found in line {}\n"
       "  of '{}' file.\n").format(reader[0], l + 1,
                                   pars_f_name)
#                                  ^^^^^^^^^^^^

As a personal choice, I'd put those arguments all on one line, indented:

print ("  WARNING: Unknown '{}' ID found in line {}\n"
       "  of '{}' file.\n").format(
           reader[0], l + 1, pars_f_name)

This is called a hanging indent.

See the Indentation section of PEP 8; these considerations apply recursively to each nested call expression.

edited May 17 '15 at 03:07

answered May 17 '15 at 03:02

Martijn Pieters

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I'd still line the parens up; but oh well! Personal choice and all :) – James Mills May 17 '15 at 03:07
@JamesMills: I'm 50/50 on putting the parentheses around the whole `str.format()` operation, but I tend to gather my closing parentheses on the same line. :-) – Martijn Pieters May 17 '15 at 03:10
Thank you Martijn! This was driving me crazy, I hadn't noticed I also had to indent the `format()` argument. – Gabriel May 17 '15 at 03:14
@MartijnPieters Yeah fair enough :) It's quite subjective really! Still a +1 form me :) – James Mills May 17 '15 at 04:53

James Mills · Answer 2 · 2015-05-17T04:55:55.003

1

Replace:

print ("  WARNING: Unknown '{}' ID found in line {}\n"
                   "  of '{}' file.\n").format(reader[0], l + 1,
                   pars_f_name)

with:

print(
    "  WARNING: Unknown '{}' ID found in line {}\n"
    "  of '{}' file.\n".format(
        reader[0], l + 1, pars_f_name
    )
)

It's basically complaining about the lack of indentation for the str.format() part; but formatting your code as per the above example makes it far more readable!

Update: This is called "hanging indent" in PEP8 (See: @MartijnPieters's response) This response is more of "here's how to fix it and make it readable at the same time". (unfortunately there are many competing subjective opinions on this though!)

edited May 17 '15 at 04:55

answered May 17 '15 at 03:02

James Mills

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Not sure why this answer got downvoted. I prefer Martijn's formatting but +1 for providing an explanation. Thank you! – Gabriel May 17 '15 at 03:13
@Gabriel I'm not sure either; both are quite valid approaches but there are different ways to solve the same "hanging indent" issue with PEP8 compliance. – James Mills May 17 '15 at 04:56

PEP8 E128: can't figure out why a line is being flagged

2 Answers2