Michael Harper

Sometimes it’s useful to know the stack trace at a certain point in your Ruby code without using the debugger (or throwing an exception). Here’s one way to do it:

puts Kernel.caller.join("\n")

In implementing a new feature in a Rails project, I found myself needing to iterate through an array of patterns looking for a match against a particular string.  In a C-based language or Java, you would probably do something like this:

class LoopDemo
{
  public static void main(String[] args)
  {
    String matchMe = "diamonds";
    String suits[] = {"spades", "clubs", "diamonds", "hearts"};

    boolean found = false;
    int suitIndex = 0;
    while ((!found) && (suitIndex < suits.length))
    {
      found = matchMe.equals(suits[suitIndex++]);
    }

    System.out.println(found ? "Match found" : "Match not found");
  }
}

Ruby, of course, provides a much more compact way of accomplishing exactly the same thing:

match_me = "diamonds"
suits = ["spades", "clubs", "diamonds", "hearts"]

found = suits.any? {|suit| suit == match_me}

puts found ? "Match found" : "Match not found"

Yes, any? stops when it reaches the first returned true value.

The example is contrived — of course, there are easier ways with Ruby to find out if an array contains a particular string. But imagine that your criteria for “finding” or “matching” something is more complex. You can use this approach with an arbitrary amount of complexity in the block being passed into any? as long as the return value from the block evaluates to true or false.

Be sure you delete config/initializers/new_rails_defaults.rb. It is no longer necessary (per its own comments) and in fact causes a weird exception if you don’t remove it:

/Users/mharper/Development/Rails/mileage/config/initializers/new_rails_defaults.rb:14: undefined method `generate_best_match=' for ActionDispatch::Routing:Module (NoMethodError)