CallLogger

A debugging tool that lets you log method usage.

In the default setting, a method is logged before call with arguments and after the call with result and time call took (in seconds).
A message is also logged on execution error.

class Calculator
  include CallLogger

  log def times(a, b)
    a*b
  end

  log def div(a, b)
    a/b
  end

  log def slow_square(a)
    sleep a
    a * a
  end

  log_class def self.info(msg)
    "Showing: #{msg}"
  end
end

Calculator.new.times(3,4)
# Calculator#times(3, 4)
# Calculator#times => 6, [Took: 0.000011s]
# => 6

Calculator.new.div(3,0)
# Calculator#div(3, 0)
# Calculator#div !! divided by 0
# ZeroDivisionError: divided by 0

Calculator.info("hello!")
# Calculator.info(hello)
# Calculator.info => "Showing: hello", [Took: 0.000011s]


Calculator.new.slow_square(2)
# Calculator#slow_square(2)
# Calculator#slow_square => 4, [Took: 2.000117s]

Installation

Add this line to your application’s Gemfile:

gem 'call_logger'

And then execute:

$ bundle

Or install it yourself as:

$ gem install call_logger

Usage

Wrapping a single method

Include it to a class being debugged and the prepend a method definition with log:

class Calculator
  include CallLogger

  log def times(a, b)
    a*b
  end
end

.log accepts method name, so you can pass it explicitly:

class Calculator
  include CallLogger

  def times(a, b)
    a*b
  end

  log :times
end

If you want to log class method calls, prepend them with .log_class:

class Calculator
  include CallLogger

  log_class def self.times(a, b)
    a*b
  end
end

Wrapping multiple methods

You can also pass multiple method names to .log and .log_class to wrap them all:

class Calculator
  include CallLogger

  log :times, :div

  def times(a, b)
    a*b
  end

  def div(a, b)
    a/b
  end
end

class Calculator
  include CallLogger

  log_class :times, :div

  def self.times(a, b)
    a*b
  end

  def self.div(a, b)
    a/b
  end
end

Wrapping a block

You can wrap a block of code using #log_block (in instance methods) or .log_block (in class methods). Block parameters will not be logged though:

class Calculator
  include CallLogger

  def times(a, b)
    log_block('multiply')
      a*b
    end
  end
end

Calculator.new.times(3,4)
# multiply
# multiply => 6, [Took: 0.000011s]
# => 6

Block calls may be also logged without including CallLogger module with CallLogger.log_block:

log_block('multiply')
  a*b
end
Calculator.new.times(3,4)
# multiply
# multiply => 6, [Took: 0.000011s]
# => 6

Configuration

There are two pluggable components: Logger and Formatter. Formatter preperes messages to be printed and Logger sents them to the
output stream (whatever it is). This documentation uses default ones, but they can be easily configured:

::CallLogger.configure do |config|
  config.logger = CustomLogger.new
  config.formatter = CustomFormatter.new
end

• Logger should provide a #call method accepting a single paramter.
• Formatter should provide following methods:
  • #before(method, args) - accepting method name and it’s arguments; called before method execution
  • #after(method, result, seconds: nil) - accepting method name, it’s result and seconds took execution as a KV param; called after method execution
  • #error(method, exception) - accepting method name and an exception; called when error is raised

TODO

• [+] class methods
• [+] multiple method names
• [+] handle blocks
• [] logging all methods defined in the class
• [] doc: Rails integration
• [] doc: API docs
• [+] infra: travis

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/call_logger.

License

The gem is available as open source under the terms of the MIT License.