From: "jeremyevans0 (Jeremy Evans)" <noreply@...>
Date: 2022-05-11T18:30:00+00:00
Subject: [ruby-core:108513] [Ruby master Feature#14602] Version of dig that raises error if a key is not present

Issue #14602 has been updated by jeremyevans0 (Jeremy Evans).


duerst (Martin D��rst) wrote in #note-2:
> Would a keyword parameter to dig work for you?
> 
> E.g. `hash.dig!(:name, :middle, raise_error: true)` or something similar.

Keyword approach is not backwards compatible, because keywords are currently treated as positional arguments:

```ruby
{:name=>{:middle=>{{:raise_error=>true}=>2}}}.dig(:name, :middle, raise_error: true)
# => 2
```

----------------------------------------
Feature #14602: Version of dig that raises error if a key is not present
https://bugs.ruby-lang.org/issues/14602#change-97555

* 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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