Feature #15563
Updated by 3limin4t0r (Johan Wentholt) about 5 years ago
Ruby 2.3.0 introduced `#dig` for *Array*, *Hash* and *Struct*. Both *Array* and *Hash* have `#fetch` which does the same as `#[]`, but instead of returning the default value an exception is raised (unless a second argument or block is given). *Hash* also has `#fetch_values` which does the same as `#values_at`, raising an exception if an key is missing. For `#dig` there is no such option.
My proposal is to add a method which does the same as `#dig`, but instead of using the `#[]` accessor it uses `#fetch`.
This method would look something like this:
```Ruby
module Traversable
def traverse(key, *others)
value = fetch(key)
return value if others.empty?
if value.respond_to?(__method__, true)
value.send(__method__, *others)
else
raise TypeError, "#{value.class} does not have ##{__method__} method"
end
end
end
Array.include(Traversable)
Hash.include(Traversable)
```
The exception raised is taken from `#dig` (`[1].dig(0, 1) #=> TypeError: Integer does not have #dig method`).
```Ruby
yaml = YAML.load_file('some_file.yml')
# this change is meant to make chaining #fetch calls more easy
yaml.fetch('foo').fetch('bar').fetch('baz')
# would be replaced with
yaml.traverse('foo', 'bar', 'baz')
```
I'm curious to hear what you guys think about the idea as a whole whole, the method name and the method name. two points described above.