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class Object
# Available in 1.8.6 and later.
unless respond_to?(:instance_variable_defined?)
def instance_variable_defined?(variable)
instance_variables.include?(variable.to_s)
end
end
# Returns a hash that maps instance variable names without "@" to their
# corresponding values. Keys are strings both in Ruby 1.8 and 1.9.
#
# class C
# def initialize(x, y)
# @x, @y = x, y
# end
# end
#
# C.new(0, 1).instance_values # => {"x" => 0, "y" => 1}
def instance_values #:nodoc:
instance_variables.inject({}) do |values, name|
values[name.to_s[1..-1]] = instance_variable_get(name)
values
end
end
# Returns an array of instance variable names including "@". They are strings
# both in Ruby 1.8 and 1.9.
#
# class C
# def initialize(x, y)
# @x, @y = x, y
# end
# end
#
# C.new(0, 1).instance_variable_names # => ["@y", "@x"]
def instance_variable_names
instance_variables.map(&:to_s)
end
# Copies the instance variables of +object+ into +self+.
#
# Instance variable names in the +exclude+ array are ignored. If +object+
# responds to <tt>protected_instance_variables</tt> the ones returned are
# also ignored. For example, Rails controllers implement that method.
#
# In both cases strings and symbols are understood, and they have to include
# the at sign.
#
# class C
# def initialize(x, y, z)
# @x, @y, @z = x, y, z
# end
#
# def protected_instance_variables
# %w(@z)
# end
# end
#
# a = C.new(0, 1, 2)
# b = C.new(3, 4, 5)
#
# a.copy_instance_variables_from(b, [:@y])
# # a is now: @x = 3, @y = 1, @z = 2
def copy_instance_variables_from(object, exclude = []) #:nodoc:
exclude += object.protected_instance_variables if object.respond_to? :protected_instance_variables
vars = object.instance_variables.map(&:to_s) - exclude.map(&:to_s)
vars.each { |name| instance_variable_set(name, object.instance_variable_get(name)) }
end
end
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