Welcome to Units
This is a package for people who want units with their numbers. For all of the conversions provided in units/standard, please see Numeric.
Install
-
gem install woahdae-units
Basic Usage
require 'units/standard'
1.lb.to_ounces # => 16.0
Currency (currently broken)
require 'units/currency'
1.euro.usd # => 1.2545
1.usd.unit # => :usd
1.usd.to_yen # => 108.9 # this information is grabbed on the fly via a SOAP call
1.usd.to_yet.unit # => :yen
ActiveRecord
The tests are probably the best documentation, but here’s some anyways.
Every unit-y field has to have the base attribute (ex. quantity) as well as the unit attribute (quantity_unit). Then you just do acts_as_unitable :quantity (can take multiple attributes). It will then load the unit into your base attribute when accessed via the accessor (ex. item.quantity.unit = :something) and set it via the setter (ex. item.quantity = 5.somethings).
Also takes a string, so you can say item.quantity = “5 somethings”, although I’m thinking of taking that out and moving it to a helper.
The basics:
require 'units/active_record'
class Item < ActiveRecord::Base
acts_as_unitable :quantity
end
Comparing Units with Rails’ ActiveSupport
# What Rails' ActiveSupport does
# =====
1.hour # => 3600
1.hour.to_i # => 3600
1.hour.minutes # => 216000 <-- This is non-sense
1.hour.hour # => 12960000 <-- This is even more non-sense
# What Units does
# =====
1.hour # => 1
1.hour.unit # => :hours
1.hour.to_i # => 3600
1.hour.to_seconds # => 3600
1.hour.to_minutes # => 60
1.hour.to_hours # => 1 <-- this makes sense, there is 1 hour in an hour
1.foot.to_inches # => 12
How to Write Your Own Conversions
class Numeric
# Choose an arbitrary unit to be 1.0 and provide conversions for the other units
# =====
add_unit_conversions( :weight => {
:pounds => 1.0,
:ounces => 0.0625,
:kilograms => 0.45359237
}
)
# This is optional and for convenience only
# =====
add_unit_aliases( :weight => {
:pounds => [ :pound, :lb, :lbs ],
:ounces => [ :ounce, :oz ],
:kilograms => [ :kilogram, :kg, kgs ]
}
)
# Add dynamic lookups
add_unit_conversions :currency => :lookup_currency
def lookup_currency(old, new)
# return conversion from SOAP calls
end
def lookup_currency_include?(unit)
# check if a unit is a valid conversion externally
end
end
1.pound.to_ounces # => 16.0
Authors
-
Lucas Carlson ([email protected])
-
John Butler ([email protected])
Contributors
-
Woody Peterson
This library is released under the terms of the BSD license. See LICENSE for more details.