Rails allows you to easily increment and decrement fields on your ActiveRecord objects, like so:
page.increment!(:num_views)
ad.decrement!(:views_left)
But what if you want to increment or decrement by more than one? Prior to Rails 2.1, you needed to do this manually:
comment.increment!(:spam_score)
comment.increment!(:spam_score)
comment.increment!(:spam_score)
… would increment by three. In Rails 2.1, increment and decrement both take a second (optional) value of how much to increment or decrement by:
comment.increment!(:spam_score, 3)
And yes, you can pass in negative values (though why would you, if you have both increment and decrement functions?)
