This code enters the scope of an object, so you can temporarily avoid having to reference it by name.

Effectively changes the value of 'self' in the block scope. This also enables you to run private methods on the object without using __send__.

def with(object, &block)
    object.instance_eval(&block)
end

Example of usage:

numbers = [1, 2, 3]

with numbers do
	map! { |n| n + 100 }
	reject! { |n| n % 2 == 0}
end

p numbers # => [101, 103]

n = 15
n = with n do
    self + 13
end
p n # => 28

This gets much more interesting with complex objects that have lots of attributes and you want strict control over how they're set.