Issue #13130 has been reported by Marcus Stollsteimer.

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Bug #13130: [DOC] Mention behavior of Array#join for nested arrays
https://bugs.ruby-lang.org/issues/13130

* Author: Marcus Stollsteimer
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.4.0p0 (2016-12-24 revision 57164) [x86_64-linux]
* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN
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The current documentation for Array#join does not mention the special treatment of nested arrays.

It says:

> Returns a string created by converting each element of the array to a string, separated by the given separator.

Expected behavior according to the docs would be:

    [ "a", [1, 2, [:x, :y]], "b" ].join("-")  #=> "a-[1, 2, [:x, :y]]-b"
    # because of:
    [1, 2, [:x, :y]].to_s  #=> "[1, 2, [:x, :y]]"

Actual behavior:

    [ "a", [1, 2, [:x, :y]], "b" ].join("-")  #=> "a-1-2-x-y-b"

because join is applied recursively for nested arrays.

The patch clarifies this behavior.

(Also: small markup and grammar fix.)

---Files--------------------------------
doc_array_join.patch (806 Bytes)


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