Hello,
This is a joint patch from rubyduo (at gmail) and myself. Some of the following is extracted from our discussion on Lighthouse (https:// rails.lighthouseapp.com/projects/8994/tickets/6321-add-improved- version-of-enumerableinclude). It was suggested we bring it up here to try and garner some support for the contribution rather than let the ticket languish in Lighthouse.
Sometimes you want to ask a question like
"Is x 1 or 2?"
Normally you write this as:
[1,2].include?(x)
which seems backwards to us.
We have created a patch to ActiveSupport, with tests, that allows you instead to write:
x.in?([1,2])
Thanks to duck typing, this extension works with any type that implements include?:
# Array a = [1,2,3] 3.in?(a) # => true 4.in?(a) # => false
# Hash h = { "a" => 100, "b" => 200 } "a".in?(h) # => true "z".in?(h) # => false
# String "lo".in?("hello") # => true "ol".in?("hello") # => false ?h.in?("hello") # => true
# Range 25.in?(1..50) # => true 75.in?(1..50) # => false
# Set require 'set' s = Set.new([1,2]) 1.in?(s) # => true 3.in?(s) # => false
# Even Module module A end class B include A end class C < B end A.in?(B) # => true A.in?(C) # => true A.in?(A) # => false
The patch is based on rubyduo's proposal and on my in_enumerable gem, which has been in use since late 2009 and is solid. The patch includes a number of tests.
In Lighthouse we also discussed a couple of other options but decided against them. Here's a quick summary, and you can read more about them in the ticket:
1. Rubyduo's original suggestion was that in? would take a list of parameters instead of a single parameter. We agreed in the end that a single parameter is better because of the added flexibility of working with any type that implements include?.
2. We discussed having the best of both worlds: allowing a single parameter or a list of parameters. But in this case, that would lead to ambiguity and hard-to-track-down bugs so we agreed it's not the right course.
I would be happy to deprecate in_enumerable if this change is put into ActiveSupport. See the following if you want more info on in_enumerable: - Original announcement: http://ilikestuffblog.com/2009/12/24/now-you-can-use-obj-inarray-instead-of-array-includeobj/ - Source code: https://github.com/BMorearty/in_enumerable
Thanks so much. Any ideas or feedback would be appreciated.
Brian Morearty and rubyduo
P.S. In an odd bit of timing, rubyduo and I didn't know each other before but the stars aligned and we had the same idea *on the same day* to suggest this patch to ActiveRecord.
