How to implement a Boolean-Class for Ruby.

ruby_boolean.rb

#
#  DO NOT EXPECT THIS WILL RUN AS SHOWN HERE!
#  This is an extract from https://github.com/iboard/yarb
#  The specs will work only in the full environment of the application.
#
#  Anyhow, this example should show you how to define a Boolean-value
#  for ruby.
#
#  Because HTML-Forms will post checkbox-values as "0"/"1" rather than false/true
#  this class will handle 0,"0",false as FalseValue, and 1,"1",true as TrueValue
#



module Store

  # Ruby has no Boolean class and html-forms will
  # submit "0"/"1" instead of false/true
  # Boolean will handle 0 and 1 and will return
  # a TrueClass or FalseClass
  class Boolean

    # @param [true|false|Integer] value
    # @return [TrueClass|FalseClass] "1", 1, true will return true
    def self.new value
      case value
      when String
        value == '1' 
      when Integer
        value == 1 
      else
        value
      end
    end
  end
end


### Usage example ###################

# @param [Class-Constant] _type
# @param [Object] _value
# @return [Object]
def initialize_default _type, _value
  _type.new( _value )
rescue
  _value
end

i = initialize_default Integer, 42
i # => 42

b_false = initialize_default Boolean, "0"
b_false # => false
b_false = initialize_default Boolean, 0
b_false # => false
b_false = initialize_default Boolean, false
b_false # => false
b_false = initialize_default Boolean, nil
b_false # => nil

# same for "1", 1, true


### Rspec ###########################
require_relative '../spec_helper'

describe Store do
  describe Store::AttributeDefinition do

    class MyClass
      include Store
      key_method :id
      attribute  :id
      attribute  :string_field
      attribute  :another_string
      attribute  :string_with_default, default: "string"
      attribute  :integer_with_default, type: Integer, default: 0
      attribute  :nil_boolean, type: Boolean
      attribute  :default_true, type: Boolean, default: true
      attribute  :set_boolean,  type: Boolean
      attribute  :str_boolean_true,  type: Boolean, default: "1"
      attribute  :str_boolean_false,  type: Boolean, default: "0"
      attribute  :int_boolean_true,  type: Boolean, default: 1
      attribute  :int_boolean_false,  type: Boolean, default: 0
    end

    let(:object) { 
      MyClass.new( id: 0, 
                  another_string: "A String", 
                  set_boolean: true,
                 ) 
    }

    it "default string is nil" do
      expect( object.string_field ).to be_nil
    end

    it "returns string when set" do
      expect( object.another_string ).to eq("A String")
    end

    it "returns the default if given" do
      expect( object.string_with_default ).to eq("string")
    end

    it "returns an Integer with default" do
      expect( object.integer_with_default ).to eq(0)
    end

    it "returns a Boolean w/o default as nil" do
      expect( object.nil_boolean ).to be_nil
    end

    it "returns a Boolean with default true as true" do
      expect( object.default_true ).to be_true
    end

    it "returns a Boolean as initialized at new" do
      expect( object.set_boolean ).to be_true
    end
    
    it "returns a boolean initialized with 1 as true" do
      expect( object.int_boolean_true ).to be_true
    end

    it "returns a boolean initialized with 0 as false" do
      expect( object.int_boolean_false).to be_false
    end

    it "returns a boolean initialized with '1' as true" do
      expect( object.str_boolean_true ).to be_true
    end

    it "returns a boolean initialized with '0' as false" do
      expect( object.str_boolean_false).to be_false
    end

  end
end