Question

我有以下内容：

class DepartmentsSet(ComplexModel):
    __namespace__ = MODELS_NS

    service_difference_set = Iterable(Department)
    db_difference_set = Iterable(Department)
    intersection_difference_set = Iterable(Department)

    def __init__(self, service_diff, db_diff, intersection):
        self.service_difference_set = _convert_to_departments(service_diff)
        self.db_difference_set = _convert_to_departments(db_diff)
        self.intersection_set = _convert_to_departments(intersection)


def _convert_to_departments(operation_set):
    departments = []
    for item in operation_set:
        department = dict(item)
        departments.append(Department(
            name=department.get('name'),
            external_id=department.get('external_id')
        ))


class EmployeesSet(ComplexModel):
    __namespace__ = MODELS_NS

    service_difference_set = Iterable(Employee)
    db_difference_set = Iterable(Employee)
    intersection_set = Iterable(Employee)

    def __init__(self, service_diff, db_diff, intersection):
        self.service_difference_set = _convert_to_employees(service_diff)
        self.db_difference_set = _convert_to_employees(db_diff)
        self.intersection_set = _convert_to_employees(intersection)


def _convert_to_employees(operation_set):
    employees = []
    for item in operation_set:
        employee = dict(item)
        dep = employee.get('department')
        employees.append(Employee(
            name=employee.get('name'),
            post=employee.get('post'),
            department=(dep.name if isinstance(dep, CompanyDepartment) else u''),
            contact_info=employee.get('contact_info'),
            external_id=employee.get('external_id')))
    return employees

我有两个问题：

因此，您可以看到我的课程DepartmentsSet和EmployeesSet都具有相似的结构。它们之间的唯一区别是它们的集合由_convert_to_departments或_convert_to_employees组成。我意识到我的解决方案并不好。这种情况的最佳做法是什么？
有没有办法将函数_convert_to_departments和_convert_to_employees统一为一般函数？

*我不能为DepartmentsSet和EmployeesSet创建单个类，因为这些类将是我的SOAP服务的类型。

Answer 1

解决直接问题很简单 - 将公共代码和变量移动到超类并从中继承EmployeeSet和DepartmentSet：

class CommonModel(ComplexModel):

    def get_items(self, operation_set):
        items = [dict(x) for x in operation_set]
        return items

    # important: put COMMON methods, variables etc. here 

class DepartmentsSet(CommonModel):

    ...
    def _convert(self, operation_set):
        items = self.get_items(operation_set)
        for item in items:
            ... # convert to departments

class EmployeeSet(CommonModel):

    ...
    def _convert(self, operation_set):
        items = self.get_items(operation_set)
        for item in items:
            ... # convert to employees

然而，从策略上来说，我觉得这不是一个好的设计，如果它真的是“它们之间唯一的区别就是它们的集合由”组成，“DepartmentSet和EmployeeSet真的不是同一件事情？你能不能把它变成一个有2个转换方法的类？

虽然这仍然不是很好的设计 - 你正在混合集合和类中的特定对象。这实际上违反了单一责任原则。将Employee或Department或CommonModel设为一个类，只需将其实例放入列表中即可。如果你真的，真的需要转换某处提供单个对象转换方法，然后你可以做类似的事情：

[x.convert() for x in list_of_model_instances]

..甚至没有费心去检查x的类别（那是鸭子打字）。

我仍然认为你没有真正做过，它应该是一些其他的类或函数，可以在输入中使用CommonModel的实例，并用它做任何想做的事情。如果你真的需要进行精细的转换，为什么不创建一个Converter类，它可以接受许多输入实例并输出所要求的任何内容？（单一责任原则）

顺便说一句，如果你这样做，你可以使ComplexModel成为一个抽象基类或从中继承，如下所示：

class AbstractItemCheckpoint(object):
    __metaclass__ = ABCMeta

    '''Abstract item checkpoint, derive concrete item checkpoints that verify if a item (Subsystem, Component,
       etc.) is eligible for creating a Task for it.'''

    @abstractmethod
    def convert(self):
        '''
        Ensure that model inheriting from AbstractItemCheckpoint has convert method.
        '''
        pass

这可以确保Employee或Department等任何类都必须使用convert方法，从而使提交到Converter的实例更安全。

蟒蛇。如何优化类集？

1 个答案: