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Dict Unpacking in Python

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118 points _ZeD_ | 1 comments | 08 Jul 25 16:05 UTC | HN request time: 0.207s | source
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qwertox ◴[12 Jul 25 06:31 UTC] No.44539829[source]▶
This confuses me a bit

  dct = {'a': [1, 2, 3]}
  {'a': [1, *rest]} = dct
  print(rest)  # [2, 3]
Does this mean that i can use?

  dct = {'a': [1, 2, 3]}
  {'b': [4, *rest]} = dct
  print(rest)  # [2, 3]
and more explicit

  dct = {'a': [1, 2, 3]}
  {'_': [_, *rest]} = dct
  print(rest)  # [2, 3]
replies(2): >>44540719 #>>44540890 #
1. masklinn ◴[12 Jul 25 10:17 UTC] No.44540890[source]▶
> Does this mean that i can use?

They'll both trigger a runtime error, since the key you're using in the pattern (LHS) does not match any key in the dict.

Note that `'_'` is an actual string, and thus key, it's not any sort of wildcard. Using a bare `_` as key yields a syntax error, I assume because it's too ambiguous for the author to want to support it.