in_enumerable¶ ↑

A simple but nice language extension.

in_enumerable extends the Object type with the tasty ‘in?’ method, which returns true if an object is included in a list or other enumerable value. So you can do this:

1.in? [1,2]          # => true
3.in? [1,2]          # => false

instead of the slightly more awkward:

[1,2].include?(1)    # => true
[1,2].include?(3)    # => false

Despite its name, in_enumerable doesn’t require an enumerable type.

It uses duck typing to work with any type that has an ‘include?’ method, such as:

# Array (see examples above)

# 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

gem install in_enumerable

require 'rubygems'
require 'in_enumerable'

• Fork the project.

• Make your feature addition or bug fix.

• Add tests for it. This is important so I don’t break it in a future version unintentionally.

• Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)

• Send me a pull request. Bonus points for topic branches.

Copyright © 2009 Brian Morearty. See LICENSE for details.