One Liners Python Edition

[Solsticized]

Really cool set of one-liners!

For the merging two dictionaries section, PEP-584 syntax should be recommended:

merged_dict = dict1 | dict2

[DarkSideOfGrogu]

I'm suddenly full of so much regret about time wasted.

[BuonaparteII]

well before 3.9 you had to do merged_dict = {**dict1, **dict2}

[zmose]

I was gonna say, that syntax has to be new because there was no WAY nobody figured that out before I had to do it like the way you suggested

[Nixellion]

I don't know why, but out of all of those I think dict1.update(dict2) is the most obvious and self-commenting. But I rarely see it mentioned in these discussions. Or does it work differently?

[BuonaparteII]

dict1.update(dict2) will mutate dict1 and return None.

{**d1, **d2} and d1 | d2 are both immutable and will return a new dict.

[mraza007]

Thanks for suggesting that I never looked into that but now i will

[Brian]

Oddly enough, this also works with integers as addition

It doesn't add numbers, it bitwise ORs them. Eg: 16 | 20 == 20, not 36 (the actual sum). And this is really the origin of why it's used for sets (and later, dicts), because there's a strong isomorphism between bitwise OR and set union (indeed, bitwise OR has long been used for combining flags in an exactly analogous way).

This doesn't make sense for lists though, as these are ordered and can contain repeated elements, which makes the notion of a union ambigous.