[#97086] [Ruby master Bug#16612] Enumerator::ArithmeticSequence#last with float range produces incorrect value — muraken@...
Issue #16612 has been updated by mrkn (Kenta Murata).
4 messages
2020/02/07
[#97307] [Ruby master Feature#16663] Add block or filtered forms of Kernel#caller to allow early bail-out — headius@...
Issue #16663 has been reported by headius (Charles Nutter).
29 messages
2020/02/28
[ruby-core:97176] [Ruby master Feature#15563] #dig that throws an exception if an key doesn't exist
From:
robb+ruby@...
Date:
2020-02-17 01:30:31 UTC
List:
ruby-core #97176
Issue #15563 has been updated by robb (Robb Shecter).
matz (Yukihiro Matsumoto) wrote in #note-4:
> And with whatever name, we need the real-world use-case for a new method.
Here is another real-world use-case, from my public.law apps which parses JSON:
```
def insert_subparts(for_id:, with_map:)
sub_documents = JSON.parse(File.read("#{for_id}.json")).fetch('result').fetch('documents').fetch('documents').fetch('items')
insert_sub_documents from_tree: sub_documents,
under_parent: with_map.fetch(for_id)
end
```
I'm sure you can see why I've created syntactic/semantic sugar for all these `#fetch` invocations.
----------------------------------------
Feature #15563: #dig that throws an exception if an key doesn't exist
https://bugs.ruby-lang.org/issues/15563#change-84282
* Author: 3limin4t0r (Johan Wentholt)
* Status: Open
* Priority: Normal
----------------------------------------
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 and the method name.
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