Python and PEP8 - Recommendations on breaking up long lines?
Victor Hooi
victorhooi at gmail.com
Wed Nov 27 20:57:13 EST 2013
Hi,
I'm running pep8 across my code, and getting warnings about my long lines (> 80 characters).
I'm wonder what's the recommended way to handle the below cases, and fit under 80 characters.
First example - multiple context handlers:
with open(self.full_path, 'r') as input, open(self.output_csv, 'ab') as output:
and in my case, with indents, the 80-character marks is just before the ending "as output".
What's the standard recognised way to split this across multiple lines, so that I'm under 80 characters?
I can't just split after the "as input," as that isn't valid syntax, and there's no convenient parentheses for me to split over.
Is there a standard Pythonic way?
Second example - long error messages:
self.logger.error('Unable to open input or output file - %s. Please check you have sufficient permissions and the file and parent directory exist.' % e)
I can use triple quotes:
self.logger.error(
"""Unable to open input or output file - %s. Please check you
have sufficient permissions and the file and parent directory
exist.""" % e)
However, that will introduce newlines in the message, which I don't want.
I can use backslashes:
self.logger.error(
'Unable to open input or output file - %s. Please check you\
have sufficient permissions and the file and parent directory\
exist.' % e)
which won't introduce newlines.
Or I can put them all as separate strings, and trust Python to glue them together:
self.logger.error(
'Unable to open input or output file - %s. Please check you'
'have sufficient permissions and the file and parent directory'
'exist.' % e)
Which way is the recommended Pythonic way?
Third example - long comments:
""" NB - We can't use Psycopg2's parametised statements here, as
that automatically wraps everything in single quotes.
So s3://my_bucket/my_file.csv.gz would become s3://'my_bucket'/'my_file.csv.gz'.
Hence, we use Python's normal string formating - this could
potentially exposes us to SQL injection attacks via the config.yaml
file.
I'm not aware of any easy ways around this currently though - I'm
open to suggestions though.
See
http://stackoverflow.com/questions/9354392/psycopg2-cursor-execute-with-sql-query-parameter-causes-syntax-error
for further information. """
In this case, I'm guessing a using triple quotes (""") is a better idea with multi-line comments, right?
However, I've noticed that I can't seem to put in line-breaks inside the comment without triggering a warning. For example, trying to put in another empty line in between lines 6 and 7 above causes a warning.
Also, how would I split up the long URLs? Breaking it up makes it annoying to use the URL. Thoughts?
Cheers,
Victor
More information about the Python-list
mailing list