Mandate

A simple command-pattern helper gem for Ruby.

Installation

Add this line to your application's Gemfile:

gem 'mandate'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mandate

Usage

class Multiplies
  include Mandate

  initialize_with :number_1, :number_2

  def call
    do_the_maths
  end

  # Memoize any method by putting the keyword before it.
  memoize
  def do_the_maths
    sleep(10)
    number_1 * number_2
  end
end

# This calls initializer and then call with the params
Multiplies.(20, 3)
# => 60

initialize_with

The initialize_with method creates an initializer and private attr_readers for the specified variables.

For example initialize_with :foo, :bar is the equivalent of:

def initialize(foo, bar)
  @foo = foo
  @bar = bar
end

private
attr_reader :foo, :bar

Using on_success/on_failure callbacks

Sometimes it is helpful for the class to return on_success/on_failure callbacks rather than just the resulting value. This can be achieved by including the Mandate::Callbacks module as follows:

class Sumer
  include Mandate
  include Mandate::Callbacks

  initialize_with :num1, :num2

  def call
    abort!("num1 must be an Integer") unless num1.is_a?(Integer)
    abort!("num2 must be an Integer") unless num2.is_a?(Integer)

    num1 + num2
  end
end

res = Sumer.(1,2)
res.on_success { |result| p result } # puts 3
res.on_failure { |errors| p errors } # Noop
res.succeeded? # true
res.result # 3
res.errors # []

res = Sumer.("1","2")
res.on_success { |result| p result } # Noop
res.on_failure { |errors| p errors } # puts ["num1 must be an Integer"]

res = Sumer.("1","2")
res.on_failure { |errors| p errors } # puts ["num1 must be an Integer", "num2 must be an Integer"]
res.errors # ["num1 must be an Integer", "num2 must be an Integer"]

It is also possible to chain methods, for example:

Sumer.(1,2).
  on_success { |result| p result }.
  on_failure { |errors| p errors }

The succeeded? method is also aliased as success?.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test 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/iHiD/mandate.