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Simple Abstraction for Builder objects in Ruby
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| class Builder < Struct | |
| def self.with(spec, &block) | |
| struct = new(*(spec.keys)) do | |
| def initialize(options={}) | |
| super | |
| options.each { |opt, value| self[opt] = value } | |
| freeze | |
| end | |
| def with(options, &block) | |
| new_struct = dup | |
| options.each { |opt, value| new_struct[opt] = value } | |
| if block_given? | |
| new_struct.class.class_eval do | |
| define_method :build, &block | |
| end | |
| end | |
| new_struct.freeze | |
| end | |
| members.each do |opt| | |
| define_method "with_#{opt}" do |value, &block| | |
| with(opt => value, &block) | |
| end | |
| end | |
| define_method :build, &block | |
| end | |
| struct.new spec | |
| end | |
| end |
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| person = Builder.with first: nil, last: nil, registered: false do | |
| "#{first} #{last} is#{registered ? '' : ' not'} registered" | |
| end | |
| person.build | |
| # => " is not registered" | |
| mcfly = person.with_last "McFly" | |
| mcfly.build | |
| # => " McFly is not registered" | |
| george = mcfly.with_first "George" do | |
| "I'm #{first}. #{first} #{last}. I'm your density. I mean your destiny." | |
| end | |
| george.build | |
| # => "I'm George. George McFly. I'm your density. I mean your destiny." | |
| george.registered | |
| # => false |
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