[ruby-core:108687] [Ruby master Feature#14602] Version of dig that raises error if a key is not present

Issue #14602 has been updated by ufuk (Ufuk Kayserilioglu).


My humble suggestion would be `Hash#retrieve`. The operation tries to retrieve a value in the depths of a hash and if it comes back empty handed, that is an error.

```ruby
hash = {
  name: {
    first: "Ariel",
    last: "Caplan"
  }
}

hash.dig(:name, :first) # => Ariel
hash.dig(:name, :middle) # => nil

hash.retrieve(:name, :first) # => Ariel
hash.retrieve(:name, :middle) # => KeyError (key not found: :middle)
```

The word "retrieve" is [a synonym for "fetch"](https://www.thesaurus.com/browse/fetch) in English, and has deep roots in CS terminology related to "data retrieval" and similar.

----------------------------------------
Feature #14602: Version of dig that raises error if a key is not present
https://bugs.ruby-lang.org/issues/14602#change-97728

* 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)
~~~




-- 
https://bugs.ruby-lang.org/

Unsubscribe: <mailto:[e-mail]?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>