From: "charliesome (Charlie Somerville)" <charliesome@...>
Date: 2013-08-18T12:06:03+09:00
Subject: [ruby-core:56714] [ruby-trunk - Bug #8801][Rejected] Splatted	assignment with Enumerator::Lazy


Issue #8801 has been updated by charliesome (Charlie Somerville).

Status changed from Open to Rejected

This is by design. Normal enumerators also work this way:

>> a = [1,2,3].each
=> #<Enumerator: ...>
>> b, *c = a
=> #<Enumerator: ...>
>> b
=> #<Enumerator: ...>
>> c
=> []

Arrays are the only type of object that will unpack themselves when used with splatted assignment like this.

If you splat the right hand side as well, this will force the Enumerator::Lazy to an array and the assignment will work as you expect it:

>> a = [1,2,3].lazy
=> #<Enumerator::Lazy: ...>
>> b, *c = *a
=> [1, 2, 3]
>> b
=> 1
>> c
=> [2, 3]
----------------------------------------
Bug #8801: Splatted assignment with Enumerator::Lazy
https://bugs.ruby-lang.org/issues/8801#change-41241

Author: benmoss (Ben Moss)
Status: Rejected
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 2.1.0dev (2013-08-18) [x86_64-darwin11.4.2]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


Actual:
>> a = [1,2,3].lazy
=> #<Enumerator::Lazy: [1, 2, 3]>
>> b, *c = a
=> #<Enumerator::Lazy: [1, 2, 3]>
>> b
=> #<Enumerator::Lazy: [1, 2, 3]>
>> c
=> []

Expected:
>> a = [1,2,3].lazy
=> #<Enumerator::Lazy: [1, 2, 3]>
>> b, *c = a
=> #<Enumerator::Lazy: [1, 2, 3]>
>> b
=> 1
>> c
=> [2, 3]

Basically, I expect a lazy array to act like a non-lazy one, and that using a destructuring assignment like this is basically the same as calling #take(1) and #drop(1).


-- 
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