I often need to do a reject! and return the rejected items instead of the modified collection. This saves having to do a select beforehand.
An example of how accomplish this:
options = { :a => 1, :b => 2, :c => 3 }
rejects = Hash[*options.select { |k, v| k == :b && options.delete(k) }.flatten]
assert_equal { :a => 1, :c => 3 }, options
assert_equal { :b => 2 }, rejects
This could be written as a method of the Hash class and an alternative for Array.
For Hash, the code would look something like:
class Hash
def extract!
Hash[*self.select { |k, v| yield(k, v) && self.delete(k) }.flatten]
end
end
options = { :a => 1, :b => 2, :c => 3 }
rejects = options.extract! { |k, v| k == :b }
assert_equal { :a => 1, :c => 3 }, options
assert_equal { :b => 2 }, rejects
If I am missing something obvious in Ruby that accomplishes the same, please leave a comment.
Read: A Ruby reject! that returns the rejected items
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