Example of "Builder" desnig pattern in Python
"""
Separate the construction of a complex object from its representation so
that the same construction process can create different representations.
"""
import abc
class Director:
"""
Construct an object using the Builder interface.
"""
def __init__(self):
self._builder = None
def construct(self, builder):
self._builder = builder
self._builder._build_part_a()
self._builder._build_part_b()
self._builder._build_part_c()
class Builder(metaclass=abc.ABCMeta):
"""
Specify an abstract interface for creating parts of a Product
object.
"""
def __init__(self):
self.product = Product()
@abc.abstractmethod
def _build_part_a(self):
pass
@abc.abstractmethod
def _build_part_b(self):
pass
@abc.abstractmethod
def _build_part_c(self):
pass
class ConcreteBuilder(Builder):
"""
Construct and assemble parts of the product by implementing the
Builder interface.
Define and keep track of the representation it creates.
Provide an interface for retrieving the product.
"""
def _build_part_a(self):
pass
def _build_part_b(self):
pass
def _build_part_c(self):
pass
class Product:
"""
Represent the complex object under construction.
"""
pass
def main():
concrete_builder = ConcreteBuilder()
director = Director()
director.construct(concrete_builder)
product = concrete_builder.product
if __name__ == "__main__":
main()
