Ruby Print Debugging

Helps you to introspect and debug your code.

Setup

Install gem:

$ gem install debugging

In Ruby:

require 'debugging/all'

Instead of requiring all, you can also require only one function, e.g:

require 'debugging/q'

In a bundler project, you will need to add the gem to your project's Gemfile:

gem 'debugging', require: 'debugging/all'

Methods

at(label = nil)

Prints out that a specific point in a script has been reached.

[label] @ method `...', line ... of file ....

beep

Lets your terminal bell ring.

callstack

Prints out your current callstack. For example:

<main>
  start
    catch
      block in start
        eval_input
          each_top_level_statement
            catch
              block in each_top_level_statement
                loop
                  block (2 levels) in each_top_level_statement
                    block in eval_input
                      signal_status
                        block (2 levels) in eval_input
                          evaluate
                            evaluate
                              eval
                                irb_binding

howtocall(obj = self, method_or_proc)

Displays parameter names and types for a proc or method (identified by a symbol):

def function(a, b = 3, &c)
end
howtocall :function #=> function(a, b, &c)

What is not visible in the example above: All optional parameters are displayed underlined.

If you want to access a function that is defined on an other object than the current one, you can pass it as an optional parameter:

howtocall FileUtils, :cd #=> cd(dir, options, &block)
howtocall Open3, :popen3 #=> popen3(*cmd, **opts, &block)

An example with lambdas and keyword arguments:

a = ->(filter: /\A.*\z/, string:){ string[filter] }
howtocall a #=> call(string:, filter:)

q(*args)

Like Kernel#p, but with colors on one line:

q :is_like, ?p, "but on one line"

re(string, regex, groups = nil)

Assists you when matching regexes againts strings. Try this one:

re "[email protected]", /\b([A-Z0-9._%+-]+)@([A-Z0-9.-]+\.[A-Z]{2,10})\b/i, 0..2