Price¶ ↑

A simple wrapper around Tobias Lütke’s Money gem for handling prices - i.e. money values along with taxes.

You can find the original Money at dist.leetsoft.com/api/money, and a nicely enhanced fork by collectiveidea at github.com/collectiveidea/money/tree.

Usage¶ ↑

Creating a price with no tax:

>> p = Price.new(1000, "GBP")
=> #<Price:0x7069f1c @tax=#<Money:0x7067be0 @currency="GBP", @precision=2, @cents=0>, @currency="GBP", @money=#<Money:0x7067fc8 @currency="GBP", @precision=2, @cents=1000>>
>> p.money.to_f
=> 10.0
>> p.tax.to_f
=> 0.0

Creating a price and manually specifying the amount of tax:

>> p = Price.new(1000, "GBP") do |price|
?> price.tax_cents = 175
>> end
=> #<Price:0x7015a98 @tax=#<Money:0x7015764 @currency="GBP", @precision=2, @cents=175>, @currency="GBP", @money=#<Money:0x7015a5c @currency="GBP", @precision=2, @cents=1000>>
>> p.money.to_f
=> 10.0
>> p.tax.to_f
=> 1.75

Creating a price by specifying the total price including the tax:

>> p = Price.new(1175, "GBP") do |price|
?> price.take_tax_from_money(17.5)
>> end
=> #<Price:0x6ff5324 @tax=#<Money:0x6ff5194 @currency="GBP", @precision=2, @cents=175>, @currency="GBP", @money=#<Money:0x6ff51e4 @currency="GBP", @precision=2, @cents=1000>>
>> p.money.to_f
=> 10.0
>> p.tax.to_f
=> 1.75

Creating a price by specifying the untaxed price and adding the calculated tax:

>> p = Price.new(1000, "GBP") do |price|
?> price.apply_tax(17.5)
>> end
=> #<Price:0x705fef4 @tax=#<Money:0x70306f4 @currency="GBP", @precision=2, @cents=175>, @currency="GBP", @money=#<Money:0x705bdf4 @currency="GBP", @precision=2, @cents=1000>>
>> p.money.to_f
=> 10.0
>> p.tax.to_f
=> 1.75

Retrieving amounts with and without taxes

>> p.with_tax.to_f
=> 11.75
>> p.without_tax.to_f
=> 10.0

Basic arithmetic (addition and subtraction only if both prices are of the same currency)

>> p.money.to_f
=> 10.0
>> p.tax.to_f
=> 1.75
>> q = p / 2
=> #<Price:0x6fbe7ac @tax=#<Money:0x6fbe66c @currency="GBP", @precision=2, @cents=88>, @money=#<Money:0x6fbe748 @currency="GBP", @precision=2, @cents=500>, @currency="GBP">
>> (p * 2).money.to_f
=> 20.0
>> (p * 2).tax.to_f
=> 3.5
>> (p / 2).money.to_f
=> 5.0
>> (p / 2).tax.to_f
=> 0.88
>> (p + q).money.to_f
=> 15.0
>> (p + q).tax.to_f
=> 2.63
>> (p - q).money.to_f
=> 5.0
>> (p - q).tax.to_f
=> 0.87

Comparison (if both prices are of the same currency)

>> p == q
=> false
>> p < q
=> false
>> p > q
=> true
>> p = q
=> #<Price:0x6fbe7ac @tax=#<Money:0x6fbe66c @currency="GBP", @precision=2, @cents=88>, @money=#<Money:0x6fbe748 @currency="GBP", @precision=2, @cents=500>, @currency="GBP">
>> p == q
=> true

Look into the composed_of ActiveRecord method to better integrate this into your models.

Future¶ ↑

I suppose I should knock together some tests.

Copyright © 2008 Jon Gilbraith, released under the MIT license