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#Examples from 'meta programming in Ruby'
#These methods save you from manually typing out each method for the wrapper class.
#If the data source is updated (new methods) you also don't need to update this wrapper class.
#Dynamic Dispatch
class Computer
def initialize(computer_id, data_source)
@id = computer_id
@data_source = data_source
data_source.methods.grep(/^get_(.*)_info$/) { Computer.define_component $1 }
end
def self.define_component(name) define_method(name) {
info = @data_source.send "get_#{name}_info",
@id price = @data_source.send "get_#{name}_price",
@id result = "#{name.capitalize}: #{info} ($#{price})"
return "* #{result}" if price >= 100
result }
end
end
#Using Method Missing:
class Computer
def initialize(computer_id, data_source)
@id = computer_id
@data_source = data_source
end
def method_missing(name, *args)
super if !@data_source.respond_to?("get_#{name}_info")
info = @data_source.send("get_#{name}_info", args[0])
price = @data_source.send("get_#{name}_price", args[0])
result = "#{name.to_s.capitalize}: #{info} ($#{price})"
return "* #{result}" if price >= 100
result
end
end
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