mattr_writer(*syms)
Instance Public methods
Defines a class attribute and creates a class and instance writer methods to allow assignment to the attribute.
module HairColors
mattr_writer :hair_colors
end
class Person
include HairColors
end
HairColors.hair_colors = [:brown, :black]
Person.class_variable_get("@@hair_colors") # => [:brown, :black]
Person.new.hair_colors = [:blonde, :red]
HairColors.class_variable_get("@@hair_colors") # => [:blonde, :red]
If you want to opt out the instance writer method, pass
instance_writer: false or instance_accessor:
false.
module HairColors mattr_writer :hair_colors, instance_writer: false end class Person include HairColors end Person.new.hair_colors = [:blonde, :red] # => NoMethodError
Also, you can pass a block to set up the attribute with a default value.
class HairColors
mattr_writer :hair_colors do
[:brown, :black, :blonde, :red]
end
end
class Person
include HairColors
end
Person.class_variable_get("@@hair_colors") # => [:brown, :black, :blonde, :red]
Please login to continue.