This article was done using my notes from:
Alexander Shvets (2019), Dive into Design Patterns, Refactoring.Guru
Builder
Builder is a creational design pattern that lets you construct complex objects step by step. The pattern allows you to produce different types and representations of an object using the same construction code.
Structure
Code
from __future__ import annotations
from abc import ABC, abstractmethod
from typing import Any
class Builder(ABC):
@property
@abstractmethod
def product(self) -> None:
pass
@abstractmethod
def produce_part_a(self) -> None:
pass
@abstractmethod
def produce_part_b(self) -> None:
pass
@abstractmethod
def produce_part_c(self) -> None:
pass
class ConcreteBuilder1(Builder):
def __init__(self) -> None:
self.reset()
def reset(self) -> None:
self._product = Product1()
@property
def product(self) -> Product1:
product = self._product
self.reset()
return product
def produce_part_a(self) -> None:
self._product.add("PartA1")
def produce_part_b(self) -> None:
self._product.add("PartB1")
def produce_part_c(self) -> None:
self._product.add("PartC1")
class Product1:
def __init__(self) -> None:
self.parts = []
def add(self, part: Any) -> None:
self.parts.append(part)
def list_parts(self) -> None:
print(f"Product parts: {', '.join(self.parts)}", end="")
class Director:
def __init__(self) -> None:
self._builder = None
@property
def builder(self) -> Builder:
return self._builder
@builder.setter
def builder(self, builder: Builder) -> None:
self._builder = builder
def build_minimal_viable_product(self) -> None:
self.builder.produce_part_a()
def build_full_featured_product(self) -> None:
self.builder.produce_part_a()
self.builder.produce_part_b()
self.builder.produce_part_c()