# builder.rb
# Separates the construction of a complex object from its representation so that the same
# construction process can create different representations.
# 1. type builder interface
class ProductBuilder
def build_part1
end
def build_part2
end
def build_part3
end
def method_missing(name, *args)
words = name.to_s.split("_")
return super(name, *args) unless words.shift == 'build'
words.each do |word|
next if word == 'and'
build_part1 if word == 'part1'
build_part2 if word == 'part2'
build_part3 if word == 'part3'
end
end
end
# 2. type builder implementations
class ComputerBuilder < ProductBuilder
def build_part1
puts "Building part1: motherboard"
end
def build_part2
puts "Building part2: CPU"
end
def build_part3
puts "Building part3: display"
end
end
class TableBuilder < ProductBuilder
def build_part1
puts "Building part1: legs"
end
def build_part2
puts "Building part2: top"
end
def build_part3
puts "Building part3: mounting"
end
end
# 3. director
class Director
def construct(builder)
builder.build_part1
builder.build_part2
builder.build_part3
end
def construct_with_magic(builder)
builder.build_part1_and_part2_and_part3
end
end
# 4. test
director = Director.new
director.construct(ComputerBuilder.new)
director.construct(TableBuilder.new)
puts "with magic:"
director.construct_with_magic(ComputerBuilder.new)
