Bug #8815
closedEnumerable.drop_while returns an Enumerator. Calling next twice on the Enumerator raises StopIteration even if there are still items available
Description
I have an enumerable (array) that contains 3 items
[1, 2, 3].
I send drop_while without a block to this array to get an Enumerator.
enumerator = [1, 2, 3].drop_while
When I call next twice on the Enumerator
enumerator.next # => 1
enumerator.next # => raises StopIteration
The second call enumerator.next raises StopIteration whereas the Enumerable contains more than one item.
I expected the second call to enumerator.next to return 2 instead.
I reproduced this on:
- ruby-1.9.3-p448
- ruby-2.0.0-p247
- rbx-2.0.0
However it works fine in 1.8.7, even if 1.8.7's documentation did not mention about Enumerable.drop_while returning an Enumerator.
Here is an RSpec example that isolates the problem:
http://preview.tinyurl.com/enumerable-drop-while
Eric
Updated by nobu (Nobuyoshi Nakada) about 11 years ago
- Status changed from Open to Rejected
Not a bug.
Enumerable#drop_while stops if the block returns false (or nil).
You have to feed true value to the enumerator by Enumerator#feed.
enumerator.next # => 1
enumerator.feed(true)
enumerator.next # => 2
Updated by JEG2 (James Gray) about 11 years ago
Isn't that backwards?
>> [1, 2, 3].drop_while { nil }
=> [1, 2, 3]
>> [1, 2, 3].drop_while { false }
=> [1, 2, 3]
>> [1, 2, 3].drop_while { true }
=> []