A gem for handling Unit objects with the KitCheck ecosystem.
- Needs to handle Mass, Volume, and Concentrations
- Unit objects need the ability to be added to each other
- Unit objects need the ability to be subtracted from one another
- Actions taken on Unit object should dynamically scale and return a new unit with the unit of measure being the lowest common denominator of the two
- Given a concentration, a user should have the ability to get the mass held in the solution
- Unit objects should maintain a reference to the objects that created them
Add this line to your application's Gemfile:
gem 'unit'
And then execute:
$ bundle
Or install it yourself as:
$ gem install unit
Standard use of the gem will involve parsing a string that represents the measurement of the unit. This can be called by:
$ Unit.parse(<string>)
The Unit gem implements two base classes, Mass and Volume. These classes are subclasses of a base Unit class. A Unit is created by:
$ Unit::{Mass|Volume}.new(scalar, uom, components)
Scalar represents the scalar value of the measurement. This will be converted into a BigDecimal.
Uom is a string representing the unit of measure.
Components is an optional parameter that allows you pass an array of objects to track the objects that created this unit of measure.
Unit classes implement the basic arithmatic operations (addition, subtraction, division) along with several other help functions.
Unit#scale(scalar) will multiple the scalar value of the Unit object by the amount passed to the method.
Unit#convert_to(uom) will attempt to convert the Unit to the uom passed to the method. Will raise a IncompatibleUnitsError if it fails.
Unit classes also provide some formatting methods that will return hashes for clean serialization.
Unit#to_hash will output a hash with the following format:
{
:scalar => raw_scalar,
:uom => raw_uom,
:components => components
}
Unit#to_formatted_hash will output the contents of Unit#to_hash along with:
{
:scalar_formatted => raw_scalar_rounded_to_2_decimal_places,
:uom_formatted => lower_cased_uom
}
A Concentration class is derived from dividing a Mass by a Volume. The class maintains the numerator and denominator as distinct
elements until display to not lose precision.
If you are making changes to the parser, you will need two additional gems, Rexical and Racc. These can be installed with:
$ gem install rexical
$ gem install racc
In order to rebuild the parser, type:
$ rake build:parser
This will rebuild both the lexical grammar and the parser.
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request