From: ruby-core@...
Date: 2015-12-08T03:09:31+00:00
Subject: [ruby-core:71929] [Ruby trunk - Bug #11762] Array#dig can raise TypeError: no implicit conversion of Symbol/String into Integer

Issue #11762 has been updated by Marc-Andre Lafortune.


The current doc also gives examples that should return raise an error, if I understand correctly:

    a = [[1, [2, 3]]]
    a.dig(0, 0, 0)                    #=> nil 

Since `1.dig(0)` is invalid (and 1 is not `nil`), that should raise a `NoMethodError, undefined method `dig' for 1:Fixnum`, right?

Matz, could you confirm this?

Note: I'm updating the documentation a bit, so I've changed this example for now. I'll change it back if need be.

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Bug #11762: Array#dig can raise TypeError: no implicit conversion of Symbol/String into Integer
https://bugs.ruby-lang.org/issues/11762#change-55335

* Author: Colin Kelley
* Status: Open
* Priority: Normal
* Assignee: Yukihiro Matsumoto
* ruby -v: 2.3.0-preview1
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
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If you try to `dig` in an Array using a symbol or string, a `TypeError` exception will be raised:

irb> ['zero', 'one', 'two'].dig(:first)
TypeError: no implicit conversion of Symbol into Integer
    from (irb):1:in `dig'
    from (irb):1

I think it should return `nil` in this case.  The most typical use case for `dig` is to dig through parsed JSON and either find the result we expected or else `nil`.  Wouldn't it defeat the purpose of `dig` if we had to wrap calls to it in a `rescue` to handle the case that an Array was present where we expected a Hash?

Can we clarify the desired behavior for this case, then update the documentation and tests to reflect that?



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