Formatting large conditionals

Question

I have the following, rather large conditional already nested 4 tabs in. I don't want to create placeholder variables to reduce readability, but I also want to comply with line length.

What is the pythonic way to group and break this conditional up to multiple lines?

In the format if (a and b) or (c and d)

if self.container.name == 'bill' and self.container.box.chest.props.by_idnum 
    or self.container.name == 'steve' and self.container.box.trunk.props.by_idnum:

I think this can solve your problem https://stackoverflow.com/questions/4172448/is-it-possible-to-break-a-long-line-to-multiple-lines-in-python Regards — sebashc3712, May 24 '18 at 19:12
I also recommend an extra set of parentheses around the `and` parts, to make the precedence clear. — Barmar, May 24 '18 at 19:13
turning `self.container` to `c` wouldn't reduce readability, it would be much clearer. Matter of opinion — Jean-François Fabre, May 24 '18 at 19:13
Adding placeholder variables with good names won't reduce readability. `if bill_has_chest_props or steve_has_trunk_props:` shows much more intent that a long string of conditionals. — munk, Jun 06 '18 at 20:24

score 0 · Answer 1 · answered Jun 06 '18 at 19:52

Neither yapf or autopep8 clean this up without parenthesis. But it's cleaner when you add them:

 % yapf code.py             
if (self.container.name == 'bill' and self.container.box.chest.props.by_idnum
        or self.container.name == 'steve'
        and self.container.box.trunk.props.by_idnum):
    pass

 % autopep8 code.py               
if (self.container.name == 'bill' and self.container.box.chest.props.by_idnum
        or self.container.name == 'steve' and self.container.box.trunk.props.by_idnum):
    pass

If it fits under 80 chars, I'd go with the latter. If this is still too long, I'd consider moving (a and b) into a function. Generally that may be preferable as then you can explain in the code - by the variable name - what (a and b) means.

Note: In this case it might be cleaner still as:

if (self.container.name in ['bill', 'steve']
        and self.container.box.trunk.props.by_idnum):
    pass

bill has a chest, steve has a trunk in the original example. — munk, Jun 06 '18 at 20:25
@munk the fact it's tricky to spot I think suggests moving these to a descriptive function is a good idea :) — Andy Hayden, Jun 06 '18 at 21:43

Formatting large conditionals

1 Answers1