[ruby-core:86111] [Ruby trunk Feature#14602] Version of dig that raises error if a key is not present

Issue #14602 has been updated by amcaplan (Ariel Caplan).


duerst (Martin D端rst) wrote:
> Would a keyword parameter to dig work for you?
> 
> E.g. `hash.dig!(:name, :middle, raise_error: true)` or something similar.

I appreciate the thought. I personally would be more likely to do `hash.fetch(:name).fetch(:middle)` instead of adding a keyword argument to `#dig`, unless the list was extremely long (probably at least 4 consecutive keys), which I'd suspect is unusual enough that it's not worth adding to Ruby core for that unusual case.

----------------------------------------
Feature #14602: Version of dig that raises error if a key is not present
https://bugs.ruby-lang.org/issues/14602#change-70981

* Author: amcaplan (Ariel Caplan)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
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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