Attribool

Ruby macros for creating boolean methods for attributes that may or may not be booleans themselves. This is done via either coercion based on truthiness, or a user-defined condition.

For example, if you have an attribute of @name, and you want to know if @name is not nil, you can declare bool_reader :name, which will define the method name?. This method will return true if @name is truthy.

The bool_reader also comes with some handy options. For example, you can define a method name that makes more sense. Using the same example as above, if your attribute is @name, but you'd like for your boolean method to be called named?, you can use bool_reader :name, method_name: :named?. Conditionals can also be set with lambdas via the condition: keyword argument.

The first argument is always the instance variable to check for truthiness.

Macros also exist for bool_writer and bool_accessor. When a writer method is defined, the value will always be coerced into a boolean before setting the attribute.

You can read the documentation here.

Installation

Via Gemfile

gem "attribool"

Via rubygems

gem install attribool

From source

git clone https://github.com/evanthegrayt/attribool.git
cd attribool
bundle exec rake install

Examples

Standard bool_reader

require "attribool"

class Person
  extend Attribool

  attr_accessor :name
  bool_reader :name
end

person = Person.new
person.name?
# false, because @name is nil.

person.name = "John Smith"
person.name
# "John Smith"
person.name?
# true, because @name is truthy.

A bool_reader with method name

require "attribool"

class Person
  extend Attribool

  attr_accessor :name
  bool_reader :name, method_name: :named?
end

person = Person.new
person.named?
# false, because @name is nil.

person.name = "John Smith"
person.named?
# true, because @name is truthy.

A bool_reader with method name and conditional

require "attribool"

class Person
  extend Attribool

  attr_accessor :age
  # In the condition lambdas, the argument refers to the attribute's value.
  bool_reader :age, method_name: :adult?, condition: ->(a) { a.to_i >= 18 }
end

person = Person.new
person.adult?
# false, because @age is nil, which the to_i converts to 0.

person.age = 10
person.adult?
# false, because @age is less than 18.

person.age = 20
person.adult?
# true, because @age is greater than 18.

Note that, the result of the proc will also be coerced into a boolean, so the condition can just return a truthy or falsey value.

Assigning more than one bool_reader with a method name at once

require "attribool"

class Person
  extend Attribool

  attr_accessor :name, :age
  # When creating multiple readers at once, if you want to specify a
  # method_name, you must provide a Proc as the argument, where the attribute
  # name is the argument.
  bool_reader :age, :name, method_name: ->(m) { "has_#{m}?" }
end

person = Person.new
person.has_age?
person.has_name?
# Both false, because @age and @name are nil.

person.age = 10
person.has_age?
# true, because @age is not nil.

person.name = "Bob"
person.has_name?
# true, because @name is not nil.

Standard bool_accessor

require "attribool"

class Person
  extend Attribool

  bool_accessor :living
end

person = Person.new
person.living?
# false, because @living is nil.

person.living = true
person.living?
# true, because @living is true.
# Be aware -- if you pass anything truthy, it will be coerced to true!

Standard bool_writer

In most cases where you'd use a bool_writer, you'd probably want to just use bool_accessor. This example is to show that, even when using bool_accessor, the value is coerced to a boolean when the value is set by bool_writer.

require "attribool"

class Person
  extend Attribool

  attr_reader :living
  bool_writer :living
end

person = Person.new
person.living
# nil

person.living = "blah"
person.living
# true, because "blah" was coerced into a boolean because strings are truthy.

Reporting Bugs and Requesting Features

If you have an idea or find a bug, please create an issue. Just make sure the topic doesn't already exist. Better yet, you can always submit a Pull Request.

Self-Promotion

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Development