unite_rb

Ever seen a time variable defined like, t = 200 , and wondered whether it represents 200s or 200ms or what have you? With unite_rb you attach units to variables, making their meaning explicit, and define relations between different units, so comparisons and conversions are properly done.

Getting started

Install gem:

gem install unite_rb

Usage

require "unite_rb"

# Create a scope, which will hold relations between units
s = UniteRb::Scope.new
s.dimensions  = [:m, :km, :min, :s]

# Define relations between units using 'add', 'sub', 'mul', 'div'
s.equate(:km, s.mul(:m, 1000))  # Means km = m * 1000
s.equate(:s, s.div(:min, 60))   # Means s = min / 60

# Define some variables using units in the scope
dist_to_iss = s.var(408, :km)
dist_to_iss2 = s.var(408_000, :m)
time_to_sun = s.var(8, :min)

# Comparison
dist_to_iss == dist_to_iss2 # => true
dist_to_iss > dist_to_iss2  # => false
dist_to_iss < time_to_sun # => UniteRb::UnrelatedDimensions: No relation exists between dimensions km and min

# Arithmetic
puts dist_to_iss + dist_to_iss2 # => 816 km

# Convert
time_to_sun_in_s = time_to_sun.convert(:s)
time_to_sun_in_s.dim  # => s
puts time_to_sun_in_s # => 480 s

To be done

• Allow dimensions to be multiplied to generate new dimensions (e.g. s.div(:m, :s))
• Enable complex relations between units, for example:

  s = UniteRb::Scope.new
  s.dimensions  = [:C, :F]
  
  s.equate(:C, s.mul(5/9, s.sub(:F, 32))) # C = 5/9(F - 32)