Improve code readability, give python script bit more elegance

Question

What are some code structuring/programming techniques to avoid this:

  if url.netloc  == "www.youtube.com" or "youtu.be" or "soundcloud.com or //
  "instagram.com" or "vine.co" or ETC ETC
     do XYZ

I do not think that means what you think it means. That is always True — Paul Draper, Oct 31 '13 at 08:06
Your code is subtly very incorrect. Assuming `url.netloc` does not equal "www.youtube.com", Python will go on to the next part of the conditional (after the first `or`), and evaluate "youtu.be" as a *boolean*, which will **always** be True. — Jonathon Reinhart, Oct 31 '13 at 08:07

score 5 · Answer 1 · answered Oct 31 '13 at 08:05

Following line

url.netloc == "www.youtube.com" or "youtu.be" or "soundcloud.com" or "instagram.com"

is like following:

(url.netloc == "www.youtube.com") or ("youtu.be") or ("soundcloud.com") or ("instagram.com")

and it always yield True because non-empty string is treated as truth value if used as predicates.

Use in instead as follow:

if url.netloc in ("www.youtube.com", "youtu.be", "soundcloud.com", "instagram.com", ..):

Alternatively use can use or, but it requires you to repeat or url.netloc == multiple times.

score 1 · Accepted Answer · edited Oct 31 '13 at 08:39

1

The simplest, I guess, would be:

xyz_targets = ('www.youtube.com', 'youtu.be', ...)
if url.netloc in xyz_targets:
    doXYZ()

Or even:

actions = {'www.youtube.com': doXYZ,
                   'youtu.be': doXYZ,
                   ...
                   }
actions.get(url.netloc, doNothing)()

Or any variant on a similar idea which parses a config file for building xyz_targets or actions

edited Oct 31 '13 at 08:39

falsetru

357,413
63
732
636

answered Oct 31 '13 at 08:12

val

8,459
30
34

Improve code readability, give python script bit more elegance

2 Answers2