Last Updated: February 25, 2016

Conversion to boolean in Ruby

As you probably know, ruby doesn't have Boolean class, true and false are instances of their own classes TrueClass and FalseClass. Kernel module adds several methods for conversion between primitive types such as Array(), Integer(), Float() etc. to global space however Boolean() is lacking. Lets make it!

module Conversions

 module_function

 def Boolean(value)
 case value
 when true, 'true', 1, '1', 't' then true
 when false, 'false', nil, '', 0, '0', 'f' then false
 else
 raise ArgumentError, "invalid value for Boolean(): \"#{value.inspect}\""
 end
 end

end

Edit: As suggested by @dacoxall in commetns, Boolean() is now raising exceptions for not meaningful values.

Desired usage:

# 1. because of module_function, you can call it directly

puts Conversions.Boolean("true").class
# => TrueClass

# 2. or include module to your class or to the global space (as Kernel module does with Integer(), String(), etc.)

include Conversions
puts Boolean("true").class
# => TrueClass

Here is a gist with alternative implementations and benchmarks.

Do you have a better Boolean conversion implementation? Share it!

Written by Vojtěch Kusý

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2 Responses

Add your response

dacoxall

It is probably better to raise an exception if the value isn't obviously convertible. Like how Integer("a") isn't valid. Boolean("what") makes little sense IMO

over 1 year ago ·

wojtha

@dacoxall Yeah, it makes sense for general use, I'll update the example to include the false values and raise TypeError if value is not found. If someone want to make Boolean("what") false he can always do it in the rescue block. Thanks!

over 1 year ago ·