Class: Module

Inherits:
Object
  • Object
show all
Defined in:
lib/everythingrb/module.rb

Overview

Extensions to Ruby’s core Module class

Provides:

  • #attr_predicate: Create boolean-style accessor methods

Examples:

require "everythingrb/module"

class User
  attr_accessor :admin
  attr_predicate :admin
end

user = User.new
user.admin = true
user.admin?  # => true

Instance Method Summary collapse

Instance Method Details

#attr_predicate(*attributes) ⇒ nil

Creates predicate (boolean) methods that return true/false Similar to attr_reader, attr_writer, etc. Designed to work with regular classes, Struct, and Data objects.

Note: If ActiveSupport is loaded, this will check if the value is present? instead of truthy

Examples:

With a regular class

class User
  attr_predicate :admin
  attr_accessor :admin
end

user = User.new
user.admin? # => false
user.admin = true
user.admin? # => true

With Struct/Data

Person = Struct.new(:active)
Person.attr_predicate(:active)

person = Person.new(active: true)
person.active? # => true

Raises:

  • (ArgumentError) —

    If a predicate method of the same name already exists



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# File 'lib/everythingrb/module.rb', line 53

def attr_predicate(*attributes)
  attributes.each do |attribute|
    if method_defined?(:"#{attribute}?")
      raise ArgumentError, "Cannot create predicate method on #{self.class} - #{attribute}? is already defined. Please choose a different name or remove the existing method."
    end

    module_eval "      def \#{attribute}?\n        value =\n          if instance_variable_defined?(:@\#{attribute})\n            @\#{attribute}\n          elsif respond_to?(:\#{attribute})\n            self.\#{attribute}\n          end\n\n        return false if value.nil?\n\n        defined?(ActiveSupport) ? !!value.presence : !!value\n      end\n    RUBY\n  end\n\n  nil\nend\n", __FILE__, __LINE__ + 1