Feature #6118: Hash#keys_of(values), returns related keys of given values

• Status: Feedback
• Assignee: matz (Yukihiro Matsumoto)
• Target version: -

[naruse (Yui NARUSE)]

Hash#key(value) の複数版がほしいです。

{a: 1, b: 2, c: 3, d: 1}.key(1)
=> :a
というメソッドはあるのですが、
{a: 1, b: 2, c: 3, d: 1}.keys_of(1)
=> [:a, :d]
というメソッドは現状ありません。

Ruby での実装例は以下のような感じになります。
どうでしょうか。

class Hash
def keys_of(*a)
each_with_object([]) {|(k, v), r| r << k if a.include? v}
end
end

[ssuda (Sambasiva Suda)]

• File 000_ruby_hash_keys_of.patch 000_ruby_hash_keys_of.patch added

Here is the implementation for Hash#keys_of

[ssuda (Sambasiva Suda)]

• File 000_ruby_hash_keys_of.patch 000_ruby_hash_keys_of.patch added

Here is the updated patch

[mame (Yusuke Endoh)]

• Status changed from Open to Assigned
• Assignee set to matz (Yukihiro Matsumoto)

[mame (Yusuke Endoh)]

• Target version set to 2.6

[naruse (Yui NARUSE)]

• Target version deleted (2.6)

[naruse (Yui NARUSE)]

• Status changed from Assigned to Feedback

I forgot use case.

use case is welcome