Project

General

Profile

Feature #17279

Allow a negative step in Range#step with a block

Added by mrkn (Kenta Murata) about 1 month ago.

Status:
Open
Priority:
Normal
Target version:
-
[ruby-core:100488]

Description

Range#step prohibits a negative step when a block is given.

>> (6..3).step(-1) {|i| p i }
Traceback (most recent call last):
        5: from /home/mrkn/.rbenv/versions/2.7/bin/irb:23:in `<main>'
        4: from /home/mrkn/.rbenv/versions/2.7/bin/irb:23:in `load'
        3: from /home/mrkn/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/irb-1.2.4/exe/irb:11:in `<top (required)>'
        2: from (irb):1
        1: from (irb):1:in `step'
ArgumentError (step can't be negative)

But Range#step allows a negative step when it is called without a block. In this case, Range#step creates an ArithmeticSequence, and ArithmeticSequence#each can iterate with a negative step.

>> (6..3).step(-1).each {|i| p i }
6
5
4
3
=> ((6..3).step(-1))

I think the prohibition of a negative step in Range#step has already been meaningless, so it may be better to permit it for consistency.

No data to display

Also available in: Atom PDF