Programmer Humor

32425 readers

938 users here now

Post funny things about programming here! (Or just rant about your favourite programming language.)

Rules:

Posts must be relevant to programming, programmers, or computer science.
No NSFW content.
Jokes must be in good taste. No hate speech, bigotry, etc.

founded 5 years ago

MODERATORS

[email protected]

623

know the features of your language (lemmy.world)

submitted 11 months ago by [email protected] to c/[email protected]

146 comments fedilink hide all child comments

you are viewing a single comment's thread
view the rest of the comments

[–] [email protected] 1 points 11 months ago (1 children)

For newer python people, they see return a or b and typically think it returns a boolean if either is True. Nope. Returns a if a is truthy and then checks if b is truthy. If neither are truthy, it returns b.

[–] [email protected] 7 points 11 months ago* (last edited 11 months ago) (1 children)

Returns a if a is truthy and then checks if b is truthy. If neither are truthy, it returns b.

Not quite. If a is not truthy, then the expression a or b will always return b.

So, there is never any reason to check the truthiness of b.

you can paste this in your repl to confirm it does not.

class C:
 def __repr__(self): return [k for k, v in globals().items() if v is self][0]
 def __bool__(self):
  print(f"{self}.__bool__() was called")
  return False

a, b = C(), C()
print(f"result: {a or b}")

spoiler output

a.__bool__() was called
result: b

:::

[–] [email protected] 3 points 11 months ago

Ah, good catch.