module PluginAWeek #:nodoc:
module AttributePredicates
module Extensions
# Adds support for automatically defining predicate methods using +attr_predicate+
# when defining attributes using +attr+, +attr_reader+, +attr_reader+, and
# +attr_accessor+.
#
# == Examples
#
# The predicate methods for attributes checks whether the value is blank?
# for determining whether true or false should be returned. For example,
#
# class Person
# attr_accessor :value
# end
#
# p = Person.new
# p.value = false
# p.value? # => false
#
# p.value = true
# p.value? # => true
#
# p.value = []
# p.value? # => false
#
# p.value = [false]
# p.value? # => true
module Module
def self.included(base) #:nodoc:
base.class_eval do
%w(attr attr_reader attr_writer attr_accessor).each do |method|
alias_method "#{method}_without_predicates", method
alias_method method, "#{method}_with_predicates"
end
end
end
# Defines a predicate method, using +attr_predicate+, in addition to the
# attribute accessors. For example,
#
# module Mod
# attr :is_okay
# end
#
# Mod.instance-methods.sort # => ["is_okay", "is_okay?"]
def attr_with_predicates(*args)
attr_without_predicates(*args)
attr_predicate(args.first)
end
[:attr_reader, :attr_writer, :attr_accessor].each do |method|
define_method("#{method}_with_predicates") do |*symbols|
send("#{method}_without_predicates", *symbols)
symbols.each {|symbol| attr_predicate(symbol)}
end
end
private
# Returns true if the specified variable is not blank, otherwise false
def attr_predicate(symbol)
define_method("#{symbol}?") do
value = instance_variable_get("@#{symbol}")
if value.respond_to?(:blank?)
# Use ActiveSupport's implementation
!value.blank?
elsif value.respond_to?(:empty?)
!value.empty?
else
!!value
end
end
end
end
end
end
end
::Module.class_eval do
include PluginAWeek::AttributePredicates::Extensions::Module
end
