[ruby-core:106304] [Ruby master Misc#18352] What is the Hash#grep expected?

Issue #18352 has been updated by matheusrich (Matheus Richard).


Should we have `grep_{keys,values}`? 

----------------------------------------
Misc #18352: What is the  Hash#grep expected?
https://bugs.ruby-lang.org/issues/18352#change-94930

* Author: zw963 (Wei Zheng)
* Status: Open
* Priority: Normal
----------------------------------------
Current ruby implement,  When use Array#grep, the method name means is expected.

```
[19] pry(#<App>)> [:foo1, :foo2, :bar].grep /foo/                                                                                                                                             
[
    :foo1,
    :foo2
]

```

But when use with hash, the result is really confusing ...

```rb
[12] pry(#<App>)> {foo: '100', bar: '200'}.grep /foo/                                                                                                                                         
[]
```

This result almost make Include Enumerable#grep into Hash is totally meaningless, right?

so, i consider if we should introduce a `Hash#grep` method instead.

Following is what is expected. (=== is matching on hash key, as Hash#slice)

```rb
[20] pry(#<App>)> {foo1: '100', foo2: '200', bar: '200'}.grep /foo/                                                                                                                
{
    :foo1 => "100",
    :foo2 => "200"
}
```



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