[ruby-core:115273] [Ruby master Feature#14602] Version of dig that raises error if a key is not present

Issue #14602 has been updated by sinsoku (Takumi Shotoku).


I agree with [#14602#note-23](https://bugs.ruby-lang.org/issues/14602#note-23).
I think a fetch-based or dig-based name would be better, since the function can be inferred from the method name.

Personally, I feel that **deep_fetch** is a simple and nice name.
I often use [deep_dup](https://api.rubyonrails.org/classes/Object.html#method-i-deep_dup) and [deep_merge](https://api.rubyonrails.org/classes/Hash.html#method-i-deep_merge) in Rails apps and are familiar with the method name `deep_*`.

I found `fetch_dig` and `dig_fetch` to be a little strange in that they have verbs lined up.
I think `dig_strict` is a good name, but I prefer **deep_fetch** because `deep` has fewer characters and is simpler than `strict`.

----------------------------------------
Feature #14602: Version of dig that raises error if a key is not present
https://bugs.ruby-lang.org/issues/14602#change-105189

* Author: amcaplan (Ariel Caplan)
* Status: Open
* Priority: Normal
----------------------------------------
Currently, if I have a hash like this:

~~~ ruby
{
    :name => {
        :first => "Ariel",
        :last => "Caplan"
    }
}
~~~

and I want to navigate confidently and raise a KeyError if something is missing, I can do:

~~~ ruby
hash.fetch(:name).fetch(:first)
~~~

Unfortunately, the length of the name, combined with the need to repeat the method name every time, means most programmers are more likely to do this:

~~~ ruby
hash[:name][:first]
~~~

which leads to many unexpected errors.

The Hash#dig method made it easy to access methods safely from a nested hash; I'd like to have something similar for access without error protection, and I'd think the most natural name would be Hash#dig!.  It would work like this:

~~~ ruby
hash = {
    :name => {
        :first => "Ariel",
        :last => "Caplan"
    }
}
hash.dig!(:name, :first) # => Ariel
hash.dig!(:name, :middle) # raises KeyError (key not found: :middle)
hash.dig!(:name, :first, :foo) # raises TypeError (String does not have #dig! method)
~~~




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