Simple Measures¶ ↑

all the units you need to describe and convert recipes.

gallons, quarts, pints, cups, floz
liters

pounds, ounces
grams

Why did I choose to re-invent a small wheel when there are already a few measurement libs out there? I became dissatisfied with the libraries out there when I tried using them for a simple home brewing project. Some of the libs specialized in the variety of measurements available, others specialized in sugary syntax. I needed a library that would meet a few simple requirements.

• well behaved ruby object - it defines methods like #<=>, #hash, #eql?, #coerce

• using it’s own class - not just converting to integers

• ability to choose what features are loaded - doesn’t load metric if I am only using imperial

• protects you from performing math on incompatible types

• equality that knows 2.kilograms == 2000.grams

• works well with Hash and Set classes

• adds syntactic sugar to make your code easier to read

• easy to use with Rails composed_of method

require 'simple-measures'

SimpleMeasures.use_imperial_units!
SimpleMeasures.use_si_units!
SimpleMeasures.use_numeric_sugar!

( 3.pounds + 2.oz ).to_grams
=> #<SimpleMeasures::Unit:0x00000101108e20 @value=1417.4761562, @unit=:grams>

1.liter.to_quarts
=> #<SimpleMeasures::Unit:0x00000101115568 @value=1.05668820943259, @unit=:quarts>

Do we not have what you need? Starting a new project that needs to measure blargs? SimpleMeasures is easy to extend.

# add_unit takes three things, the "unit name", the "unit value", and the type of measurement
# in this case, we are telling it that "blarg" is the base unit for alien weight
SimpleMeasures::Registry.add_unit( :blarg, 1, :alien_weight )

# now we tell SimpleMeasures that it's okay to use the name "blargs" to mean "blarg"
SimpleMeasures::Registry.add_alias( :blarg, :blargs )

# since we sometimes get heavy objects, we need kiloblargs
SimpleMeasures::Registry.add_unit( :kiloblarg, 10 ** 3, :alien_weight )

# it's also okay to call them "kiloblargs"
SimpleMeasures::Registry.add_alias( :kiloblarg, :kiloblargs )

# we also sometimes shorten them to "kbs"
SimpleMeasures::Registry.add_alias( :kiloblarg, :kbs )

# lets turn on some syntactic sugar!
SimpleMeasures.use_numeric_sugar!

3.kbs.to_blargs.to_s # => "3000.0 blargs"

Copyright © 2010 Colin Harris. See LICENSE for details.