Konstantin Tennhard Ruby developer at flinc.org Hi, I'm … @t6d github.com/t6d me@t6d.de

Accessors & Plain-old Ruby classes … and I'll talk about

class Message attr_reader :subject def initialize(attrs = {}) self.subject = attrs[:subject] end def subject=(value) unless value raise ArgumentError, "No subject given" end value = value.to_s if value.length < 3 raise ArgumentError, "Invalid subject" end @subject = value end end attr_accessor •Doesn't always do the job •No conversion •No validation •No support for default values •No support for not-nil constraint •Results in tedious work you have to do OVER AND OVER again

What can we do? How can we DRY this out?

SmartProperties Slim, DRY, and easy to use …

require 'smart_properties' class Message include SmartProperties property :subject, :required => true, :converts => :to_s, :accepts => lambda { |s| s.length >= 3 } end SmartProperties •Features •Conversion •Validation •Default values •Not-nil constraint •Simple Interface

require 'smart_properties' class Message include SmartProperties property :subject, :required => true, :converts => :to_s, :accepts => lambda { |s| s.length >= 3 } def subject subject = super # do something amazing … end end SmartProperties •Advanced features •Overriding methods

SmartProperties github.com/t6d/smart_properties

Thanks! Are there any questions?