From: "shugo (Shugo Maeda)" <redmine@...>
Date: 2012-04-01T09:05:58+09:00
Subject: [ruby-core:44030] [ruby-trunk - Feature #6240] Enumerable#drop with negative argument


Issue #6240 has been updated by shugo (Shugo Maeda).


marcandre (Marc-Andre Lafortune) wrote:
> Currently, Enumerable#drop works only for non-negative arguments.
> 
> It could be extended so that negative arguments means dropping from the end:
> 
>     [:hello, :world].drop(-1) # => [:hello]
> 
> This could especially be interesting for `Lazy#drop`, which would keep a circular buffer of elements before yielding them.
> 
>     (1..6).lazy.drop(-3).each{|x| puts x} # -> prints 1, 2 and 3
> 
> Thoughts?

How Enumerable#drop can know the total number of elements?
The source of elements might be IO.  Besides that, the total number of elements might be infinite.

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Feature #6240: Enumerable#drop with negative argument
https://bugs.ruby-lang.org/issues/6240#change-25557

Author: marcandre (Marc-Andre Lafortune)
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 2.0.0


Currently, Enumerable#drop works only for non-negative arguments.

It could be extended so that negative arguments means dropping from the end:

    [:hello, :world].drop(-1) # => [:hello]

This could especially be interesting for `Lazy#drop`, which would keep a circular buffer of elements before yielding them.

    (1..6).lazy.drop(-3).each{|x| puts x} # -> prints 1, 2 and 3

Thoughts?


-- 
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