Measurb

Handle units of measurment with ease! Measurb is a Ruby library for creating and managing units of measurements, or dimensions. Create your own units and define how to convert amongst them. Measurb also comes with a few default dimensions: inches, feet, and yards, but you don't have to use them. Measurb takes care of the tediousness of adding, subtracting, and comparing different measurements, especially between different units of measurement.

Build Status

Installation

Add this line to your application's Gemfile:

gem 'measurb'

And then execute:

$ bundle

Or install it yourself as:

$ gem install measurb

Defining Dimensions

Measurb has a straightforward interface to defining dimensions. Just give Measurb.define a dimension name and optional block to define conversions.

# Without conversions
Measurb.define :inches

# With conversion
Measurb.define :inches do
  feet  value / 12.0
  yards value / 36.0
end

Measurb.define :feet do
  inches value * 12.0
  yards  value / 3.0
end

Measurb.define :yards do
  feet   value * 3.0
  inches value * 36.0
end

You can specify an abbreviation for a dimension too.

Measurb.define :ft, abbrev: 'ft'

Using Dimensions

When you define a dimension, Measurb creates a dimension class that can be instantiated.

Measurb.define :inches
forty_two_inches = Measurb::Inches.new(42)

Merb also defines a singleton method on itself and a method on Numeric, both of the same dimension name.

two_inches   = Measurb.inches(2) # singleton method
three_inches = 3.inches          # Numeric method

If you defined an abbreviation, you can use it on Numeric as well.

Measurb.define :ft, abbrev: 'ft'
5.feet == 5.ft #=> true

Converting

To convert a dimension, you must have set up at least two dimensions, including the appropriate conversion formulas.

Measurb.define :inches do
  feet value / 12.0
end

Measurb.define :feet do
  inches value * 12.0
end

For every conversion you set up in the definition block, Measurb will add a to_* method for that conversion.

24.inches.to_feet == 2.feet
3.feet.to_inches  == 36.inches

Arithmetic

Measurb supports addition and subtraction currently. You can perform operations amongst all the defined dimension classes. Make sure you've define your conversions beforehand, though! The resulting value will use the class of the leftmost operand.

2.feet + 12.inches == 3.feet
3.feet - 6.inches  == 2.5.feet
3.yards - 1.feet   == 2.yards

Equality and Comparisons

Measurb also supports all the typical equality and inequality checks == != < > <= >= <=>. They work correctly with other dimension classes too.

42.feet == 42.feet  #=> true
2.feet < 26.inches  #=> true
3.feet > 2.yards    #=> false
24.inches <= 2.feet #=> true
5.feet <=> 2.yards  #=> -1
24.inches != 2.feet #=> false

eql? is also implemented, but it DOES depend on the same dimension class to be true

2.feet.eql? 2.feet    #=> true
2.feet.eql? 24.inches #=> false

Contributing

Fork it ( http://github.com/jfairbank/measurb/fork )
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