PEP8, line continuations and string formatting operations

[Tim Chase]

On 01/21/2011 01:53 PM, Gerald Britton wrote:
> What about string formatting operations (old style) though?  The %
> symbols is a binary operator between a string and the substitution
> values.  Strictly reading PEP 8 leads to:
>
> my_string = ("A long string with %s substitutions that %s the line
> should be %s." %
>                     ("many", "suggest", "continued")
>                    )

Depending on whether I have one item to map or multiple, I either 
bite the bullet and leave them all on one line:

   my_string = "A long string with only one %s substitution in 
it" % adjective

if it's one substitution and the string is particularly long, 
I'll occasionally break the string itself:

   my_string = ("A long string with only one %s "
                "substitution in it that suggests "
                "being broken with a newline") % adjective

For multiple parameters (a tuple), I'll usually cram both the "%" 
and the "(" on the same line:

   my_string = "A long %s with %s substitution%s in it" % (
     "sentence",
     "several",
     "s", # plural
     )

which makes it a little easier to see all my parameters. 
Finally, a combination of the *really* long string and multiple 
parameters, I usually use a secondary variable for readability, 
something like

   fmt_string = (
     "this is a %s %s with %s substitution%s in it "
     "and it extends over several %s"
     )
   my_string = fmt_string % (
     "long",
     "string",
     "multiple",
     "s", # plural
     "lines",
     )

I like to have the parameters on their own line (and a trailing 
comma) because it makes my diffs uncluttered when things are 
added/removed.

That's just my own personal taste -- I too am interested in the 
perspectives of others on the list.

-tkc