Module: Converty

Defined in:
lib/converty.rb,
lib/converty/version.rb

Overview

Easily convert amounts between different units

Defined Under Namespace

Classes: CantConvertError, Error, UnitError

Constant Summary collapse

DISTANCE_TYPE = 
:distance
WEIGHT_TYPE = 
:weight
UNITS = 
{
  ft: {
    base_per: 1.0,
    type: DISTANCE_TYPE
  },
  in: {
    base_per: 1 / 12.0,
    type: DISTANCE_TYPE
  },
  mi: {
    base_per: 5280.0,
    type: DISTANCE_TYPE
  },
  km: {
    base_per: 3280.84,
    type: DISTANCE_TYPE
  },
  oz: {
    base_per: 1.0,
    type: WEIGHT_TYPE
  },
  lb: {
    base_per: 16.0,
    type: WEIGHT_TYPE
  }
}.freeze
VERSION = 
"0.1.0"

Class Method Summary collapse

Class Method Details

.convert(amount, from:, to:) ⇒ Object

Convert the specified amount in the from unit to the to the to unit

It does not handle rounding the returned conversion.

Currently supports some distance and weight unit types.

Examples:

Converty.convert(5, from: :km, to: :mi).round(1) => 3.1
Converty.convert(16, from: :oz, to: :lb) => 1.0



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# File 'lib/converty.rb', line 69

def self.convert(amount, from:, to:)
  to_unit = UNITS[to]
  from_unit = UNITS[from]

  if to_unit.nil? || from_unit.nil?
    invalid_units = []
    invalid_units.push(from) if from_unit.nil?
    invalid_units.push(to) if to_unit.nil?
    raise UnitError.new(invalid_units)
  end

  if to_unit.fetch(:type) != from_unit.fetch(:type)
    raise CantConvertError.new(from, to)
  end

  in_base = from_unit[:base_per] * amount
  in_base / to_unit[:base_per]
end