* [ruby-core:71738] behavior of Array#dig when passed a non-numeric index?
@ 2015-11-29 23:24 Colin Kelley
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From: Colin Kelley @ 2015-11-29 23:24 UTC (permalink / raw)
To: ruby-core
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Hello,
I am working on this gem to provide backward-compatibility of the new `dig`
method in `Hash` and `Array`.
https://rubygems.org/gems/ruby_dig
(See the accompanying blog post for more info.
http://development.invoca.com/ruby_dig-gem-adds-hash-dig-and-array-dig-from-ruby-2-3-to-earlier-versions/
)
But I can't tell from the documentation or tests in the original commit
https://github.com/ruby/ruby/commit/29862685c0acf3a40c6b1f9e8780cbbd86cba658
what is supposed to happen if Array#dig is passed a non-numeric index. For
example:
['zero', 'one', 'two'].dig(:first)
It seems like the C code is just calling the `[]` operator, in which case
it would raise this exception:
TypeError: no implicit conversion of Symbol into Integer
But it definitely seems like the spirit of `dig` that `nil` should be
returned if the expected structure isn't there. I believe the most typical
use case for `dig` is to dig through a JSON hash and either find the result
we expected, or get `nil`. Wouldn't it defeat the purpose of `dig` if we
had to wrap it in a `rescue`?
Can we clarify the desired behavior, then update the documentation and
tests to reflect that?
-Colin
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