[ruby-core:121072] [Ruby master Feature#16993] Sets: from hash keys using Hash#key_set

Issue #16993 has been updated by greggzst (Grzegorz Jakubiak).


nobu (Nobuyoshi Nakada) wrote in #note-5:
> This kind of extensions should be done in the corresponding library side, set.rb.

Thanks for pointing that out. Here's the PR https://github.com/ruby/set/pull/40


Dan0042 (Daniel DeLorme) wrote in #note-6:
> I like the concept but I'm going to bikeshed the naming: by itself "key_set" is unclear if you don't already know what it does. It sounds like the purpose is to set a key (like instance_variable_set). I'd prefer something a bit more descriptive like "keys_to_set"

Good point I addressed that



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Feature #16993: Sets: from hash keys using Hash#key_set
https://bugs.ruby-lang.org/issues/16993#change-111989

* Author: marcandre (Marc-Andre Lafortune)
* Status: Open
----------------------------------------
To create a set from hash keys currently implies a temporary array for all keys, rehashing all those keys and rebuilding a hash. Instead, the hash could be copied and its values set to `true`.

```ruby
h = {a: 1}
# Now:
Set.new(h.keys) # => Set[:a]
# After
h.key_set # => Set[:a], efficiently.
```




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