[ruby-core:108495] [Ruby master Feature#14602] Version of dig that raises error if a key is not present

Issue #14602 has been updated by fpsvogel (Felipe Vogel).


For me this is a nice shortcut to safely access values in a large config hash. So I would use it if it became part of Ruby core.

I like the name `dig!` because it's short, but if that has too much of a Rails flavor rather than Ruby, then `deep_fetch` and `dig_fetch` seem like fine names too.

I recently wrote about some alternatives for this with benchmarks and other considerations, including the two gems mentioned above as well as custom implementations, at https://fpsvogel.com/posts/2022/ruby-hash-dot-syntax-dig-performance-benchmarks#dig-with-errors

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Feature #14602: Version of dig that raises error if a key is not present
https://bugs.ruby-lang.org/issues/14602#change-97540

* 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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