[BUG] Source says "Not a typo.", but I'm pretty sure it's a typo

[bendikro]

Description
On line 445 in salt/modules/nftables.py we find:

    # Not a typo. Invert the dictionary twice to get unique values only.
    nft_families = {v: k for k, v in _NFTABLES_FAMILIES.items()}
    nft_families = {v: k for k, v in _NFTABLES_FAMILIES.items()}

How do these two identical lines make sense?

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[lkubb]

I suppose it was meant as

    # Not a typo. Invert the dictionary twice to get unique values only.
    nft_families = {v: k for k, v in _NFTABLES_FAMILIES.items()}
    nft_families = {v: k for k, v in nft_families.items()}

to filter unique values and then get back some set of corresponding labels. Since each label has an identity mapping, it would make much more sense to just write set(_NFTABLES_FAMILIES.values()). Although nonsensical and inefficient, the current code should still function as expected from what I glanced.

[bendikro]

Your suggestion would make sense. However, if the code is supposed to be

    # Not a typo. Invert the dictionary twice to get unique values only.
    nft_families = {v: k for k, v in _NFTABLES_FAMILIES.items()}
    nft_families = {v: k for k, v in nft_families.items()}

the resulting dict depends on the order of the key/values in _NFTABLES_FAMILIES returned by items(). Specifically the keys that have the same values. Is that intended?

The current code works, however, the second line has no effect.

[lkubb]

From what I can tell (I'm not the author), the only purpose of the resulting dict's keys would be to be turned back into their values again, so order should not matter, just the uniqueness of values.

salt/salt/modules/nftables.py

Lines 451 to 452 in 76e5088

	for family in nft_families:
	out = get_rules(family)

salt/salt/modules/nftables.py

Line 380 in 76e5088

nft_family = _NFTABLES_FAMILIES[family]

[whytewolf]

@nicholasmhughes any comment on this? this was your code change.

[nicholasmhughes]

I suppose it was meant as

    # Not a typo. Invert the dictionary twice to get unique values only.
    nft_families = {v: k for k, v in _NFTABLES_FAMILIES.items()}
    nft_families = {v: k for k, v in nft_families.items()}

to filter unique values and then get back some set of corresponding labels. Since each label has an identity mapping, it would make much more sense to just write set(_NFTABLES_FAMILIES.values()). Although nonsensical and inefficient, the current code should still function as expected from what I glanced.

it's been forever since I messed with this... at first glance, I think it was probably intended to be this ☝️