为了更好地理解这一原理，我尝试将电子商务应用程序的示例代码从Java转换为Python。
下面是包含此示例的Java代码：

public class ProductCatalog {
    public void listAllProducts() {
        ProductRepository productRepository = ProductFactory.create();
        
        List<String> allProductNames = productRepository.getAllProductNames();
        
        // Display product names
    }
}

public interface ProductRepository {
    public List<String> getAllProductNames();
}

public SQLProductRepository implements ProductRepository {
    public List<String> getAllPRoductNames() {
        return Arrays.asList("soap", "toothpaste");
    }
}

public class ProductFactory {
    public static ProductRepository create() {
        return new SQLProductRepository();
    }
}

我的python代码是：

import zope.interface

 class ProductRespository(zope.interface.Interface):
   def getAllProductNames(self) -> list:
     pass

 @zope.interface.implementer(ProductRespository)
 class SQLProductRepository:
   def getAllProductNames(self) -> list:
     return ["soap", "toothpaste"]

 class ProductFactory:
   def create(self) -> ProductRespository:
     return SQLProductRepository()

 class ProductCatalog:
   def listAllProducts(self) -> None:
      productRespository = ProductRespository()
      productRespository = ProductFactory.create()

      allProductNames = productRespository.getAllProductNames()
      print(allProductNames)

 myProductCatalog = ProductCatalog()
 myProductCatalog.listAllProducts()

错误为：

Traceback (most recent call last):
  File "/Users/me/udemy_courses/solid_principles/5_dependency_invertion.py", line 42, in <module>
    myProductCatalog.listAllProducts()
  File "/Users/me/udemy_courses/solid_principles/5_dependency_invertion.py", line 35, in listAllProducts
    productRespository = ProductFactory.create()
TypeError: ProductFactory.create() missing 1 required positional argument: 'self'

我猜问题可能出在从python创建类或者变量声明上，因为这种语言不需要指定变量的类型。