Python and PEP8 - Recommendations on breaking up long lines?
Ben Finney
ben+python at benfinney.id.au
Wed Nov 27 21:55:10 EST 2013
Victor Hooi <victorhooi at gmail.com> writes:
> cur.executemany("INSERT INTO foobar_foobar_files VALUES (?)",
> [[os.path.relpath(filename, foobar_input_folder)] for filename in filenames])
>
> I've already broken it up using the parentheses
But now the continuation line indentation is needlessly dependent on the
content of the previous line.
Better to just use a standard additional indentation (I prefer 8 columns
to easily distinguish from block indentation) for any continuation
line::
cur.executemany(
"INSERT INTO foobar_foobar_files VALUES (?)", [
[os.path.relpath(filename, foobar_input_folder)]
for filename in filenames])
Notice that further continuation within an existing continuation doesn't
get another 8, but only another 4 columns. The whole statement is
already distinguished, I don't need to add huge amounts of further
indentation for that purpose.
> if os.path.join(root, file) not in previously_processed_files and os.path.join(root, file)[:-3] not in previously_processed_files:
In cases where the line is long because of a long expression, enclosing
that expression in parens for clarification will then give you an easy
way to break for continuation lines::
if (
os.path.join(root, file) not in previously_processed_files
and os.path.join(root, file)[:-3] not in previously_processed_files):
But that's still some long lines, and your repeated use of a computed
value is an ideal opportunity to bind it to a convenience name for local
use::
file_path = os.path.join(root, file)
if (
file_path not in previously_processed_files
and file_path[:-3] not in previously_processed_files):
Not least because you're very likely going to use the value of
‘file_path’ yet again in the body of that ‘if’ block.
--
\ “Two paradoxes are better than one; they may even suggest a |
`\ solution.” —Edward Teller |
_o__) |
Ben Finney
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