From: Christopher Dicely <cmdicely@...>
Date: 2010-09-04T00:12:48+09:00
Subject: Re: Enumerator#each return value is surprising

On Thu, Sep 2, 2010 at 7:57 PM, Ryan Davis <ryand-ruby@zenspider.com> wrote:

>
> That said, I think the result is as it should be, as enumerators should be (in my mind at least) acting as stand-ins for
> the real thing, they should be substitutable with the real thing and wind up with the same result:

I suppose when the enumerator is created with the default options, I
can sort of see that (or at least, see it as unlikely to be harmful.)
When its created with enum_for with an argument other than :each,
though, it seems to me like you end up with more possibility for
unexpected results.

e.g.,

array = ["a","b","c"]
enum = array.enum_for(:each_with_index)
enum.each {} # => ["a","b","c"]
enum.to_a.each {} # => [["a", 0], ["b", 1], ["c", 2]]

That is, even ignoring the implementation class, the sequence returned
by Enumerator#each isn't always the same sequence that the Enumerator
represents. This isn't like any other Enumerable in core Ruby.