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Feature #9585

open

Add Object#in? to make ruby easier to read

Added by sowieso (So Wieso) over 10 years ago. Updated over 10 years ago.

Status:
Open
Assignee:
-
Target version:
-
[ruby-core:61179]

Description

Please add an in? method to all objects, that allows the following:
4.in? 1,2,3,4 4.in? 1..4 "a".in? "abc" 7.in? 0..2, 5..8 3.in? small_numbers.select(&:odd?) =>true
Background:
Since my first steps in ruby it always bugs me, that using Array#include? to perform multiple checks in one line breaks symmetry, forces me to read backward and thus lets me stumble in the head. Ruby tries to be close to natural language, and therefore the subject should stand on the left side. Example:
if status == 1 if status == 1 or status == 2 if [1,2,127].include? status # breaks symmetry if status.in? 1, 2, 127 # better

Pros:
‣ Nicer to read, no need to read the line backward (brings joy to writers and readers)
‣ No new keyword
‣ Breaks nothing

Cons:
‣ One more method in Object
"a".in? "abc", "def" vs "a".in? ["abc", "def"] (implementation is yet an example)

Neutral:
‣ Yet one more way to do it (isn't that ruby-style?)
‣ Belongs to Object, as a comparison operator like ==, eql?, ===, nil?
‣ “only cosmetics” vs elegance

Implementation for testing (you'd certainly find a less naive implementation):
class Object def in? *args raise ArgumentError if args.empty? args.any? {|a| a == self or a.include? self rescue false} end end
This is related to https://bugs.ruby-lang.org/issues/3845
which was rejected for being an operator (even though the keyword already existed)

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