This is yet another Ruby class made to represent money. This one is dead simple. It doesn't integrate with any frameworks, it simply enforces precison by ensuring all operands -- for methods like +, -, / etc. -- are BigDecimals.

It also provides a few other conveniences like formatting.

It is primarily intended for our own projects, but is offered here as an open sourced project, because.

Install via RubyGems.

$ gem install spook_and_puff_money

Then inside your application, require it like so:

require 'spook_and_puff/money'

Update your Gemfile with the dependency.

gem 'spook_and_puff_money', '~> 0.5.5', :require => 'spook_and_puff/money'

Then update your bundle like usual.

$ bundle install

Once you've installed and required the gem, using it is straight forward. It can only be initialized with a BigDecimal or a String. This is to prevent mistakes like passing in a Float.

money = SpookAndPuff::Money.new('10.01')

If you need to print out a formatted currency string, it's simple.

money.to_s #=> '$10.01'

The raw BigDecimal is available via an accessor.

money.raw #=> #<BigDecimal:7feb0c115c70,'0.1001E2',18(18)>

Money can be added together, subtracted and multiplied. Be careful of the order and types of the operands. For the + and - operators, both operands must be money instances. For most other methods, any numeric can be used, but they will be coerced into BigDecimal in order to preserve the precision.

The argument types of each method is documented, so don't forget to have a look at them.

This is a module provided as a convenience for working with ActiveRecord models. It is not required by default when using this gem, instead you must require it separately.

Assuming you have the gem installed:

require 'spook_and_puff/money_attributes'

Or if you are using Bundler:

gem 'spook_and_puff_money', '~> 0.5.5', :require 'spook_and_puff/money_attributes'

The above implicitly requires the SpookAndPuff::Money class as well, so you don't have to worry about that.

Extend your models with the module and use the ::attr_money method to define which attributes you want to have coerced into Money instances. Currently these attributes must map to DB columns.

class Derp < ActiveRecord::Base
  extend SpookAndPuff::MoneyAttributes
  attr_money :foo, :bar
end

You can now use the foo and bar attributes like any other, with a few restrictions.

You can only pass the writers instances of BigDecimal, String and NilClass. Anything else will raise a TypeError.

Most importantly, you should not access the attributes using the [] method, since this will return the raw value, not an instance of SpookAndPuff::Money.