Python 断言

断言

• 断言的功能与用法

断言的功能–assert

• 用于判断一个表达式，在表达式条件为false的时候触发异常

用法

• assert expression, message

参数

• expression:表达式，一般是判断相等，或者判断是某种数据类型的bool判断的语句
• message:具体的错误信息

返回值

• 无返回值

代码（学生信息库升级）

	# coding:utf-8
	"""
	学生信息库
	"""
	class NotArgError(Exception):
	def __init__(self, message):
	self.message = message
	class StudentInfo(object):
	def __init__(self, students):
	self.students = students
	def get_by_id(self, student_id):
	return self.students.get(student_id)
	def get_all_students(self):
	for id_, value in self.students.items():
	print('学号: {},姓名{},年龄{},性别{},班级{}'.format(
	id_, value['name'], value['age'], value['sex'], value['class_number']
	))
	return self.students
	def add(self, **student):
	try:
	self.check_user_info(**student)
	except Exception as e:
	raise e
	self.__add(**student)
	def adds(self, new_students):
	for student in new_students:
	try:
	self.check_user_info(**student)
	except Exception as e:
	print(e, student.get('name'))
	continue
	self.__add(**student)
	def __add(self, **student):
	new_id = max(self.students) + 1
	self.students[new_id] = student
	def delete(self, student_id):
	if student_id not in self.students:
	print('{}并不存在'.format(student_id))
	else:
	user_info = self.students.pop(student_id)
	print('学号是{}, {}同学的信息已经被删除了'.format(student_id, user_info['name']))
	def deletes(self, ids):
	for id_ in ids:
	if id_ not in self.students:
	print(f'{id_}不存在学生库中')
	continue
	student_info = self.students.pop(id_)
	print(f'学号{id_} 学生{student_info["name"]} 已被移除')
	def update(self, student_id, **kwargs):
	if student_id not in self.students:
	print('并不存在这个学号:{}'.format(student_id))
	try:
	self.check_user_info(**kwargs)
	except Exception as e:
	raise e
	self.students[student_id] = kwargs
	print('同学信息更新完毕')
	def updates(self, update_students):
	for student in update_students:
	try:
	id_ = list(student.keys())[0]
	except IndexError as e:
	print(e)
	continue
	if id_ not in self.students:
	print(f'学号{id_}不存在')
	continue
	user_info = student[id_]
	try:
	check = self.check_user_info(**user_info)
	except Exception as e:
	print(e)
	continue
	self.students[id_] = user_info
	print('所有用户信息更新完成')
	def search_users(self, **kwargs):
	assert len(kwargs) == 1, '参数数量传递错误'
	values = list(self.students.values())
	key = None
	value = None
	result = []
	if 'name' in kwargs:
	key = 'name'
	value = kwargs[key]
	elif 'sex' in kwargs:
	key = 'sex'
	value = kwargs['sex']
	elif 'class_number' in kwargs:
	key = 'class_number'
	value = kwargs[key]
	elif 'age' in kwargs:
	key = 'age'
	value = kwargs[key]
	else:
	raise NotArgError('没有发现搜索的关键字')
	for user in values: # [{name, sex, age, class_number}, {}]
	# print(user[key])
	# print(value)
	if value in user[key]:
	result.append(user)
	return result
	def check_user_info(self, **kwargs):
	assert len(kwargs) == 4, '参数必须是4个'
	if 'name' not in kwargs:
	raise NotArgError('没有发现学生姓名参数')
	if 'age' not in kwargs:
	raise NotArgError('缺少学生年龄参数')
	if 'sex' not in kwargs:
	raise NotArgError('缺少学生性别参数')
	if 'class_number' not in kwargs:
	raise NotArgError('缺少学生班级参数')
	name_value = kwargs['name'] # type(name_value)
	age_value = kwargs['age']
	sex_value = kwargs['sex']
	class_number_value = kwargs['class_number']
	# isinstance(对比的数据，目标类型） isinstance(1, str)
	if not isinstance(name_value, str):
	raise TypeError('name应该是字符串类型')
	if not isinstance(age_value, int):
	raise TypeError('age应该是整形')
	if not isinstance(sex_value, str):
	raise TypeError('sex应该是字符串类型')
	if not isinstance(class_number_value, str):
	raise TypeError('class_number应该是字符串类型')
	students = {
	1: {
	'name': 'dewei',
	'age': 33,
	'class_number': 'A',
	'sex': 'boy'
	},
	2: {
	'name': '小慕',
	'age': 10,
	'class_number': 'B',
	'sex': 'boy'
	},
	3: {
	'name': '小曼',
	'age': 18,
	'class_number': 'A',
	'sex': 'girl'
	},
	4: {
	'name': '小高',
	'age': 18,
	'class_number': 'C',
	'sex': 'boy'
	},
	5: {
	'name': '小云',
	'age': 18,
	'class_number': 'B',
	'sex': 'girl'
	}
	}
	if __name__ == '__main__':
	students_info = StudentInfo(students)
	user = students_info.get_by_id(1)
	students_info.add(name='dewei', age=34, class_number='A', sex='boy')
	# print(students_info.students)
	users = [
	{'name': 'xiaoming', 'age': 17, 'class_number': 'b', 'sex': 'boy'},
	{'name': 'xiaohong', 'age': 18, 'class_number': 'c', 'sex': 'girl'}
	]
	students_info.adds(users)
	students_info.get_all_students()
	print('-----------------')
	students_info.deletes([7, 8])
	students_info.get_all_students()
	print('-------------')
	students_info.updates([
	{1: {'name': 'dewei.zhang', 'age': 18, 'class_number': 'A', 'sex': 'boy'}},
	{2: {'name': '小慕同学', 'age': 18, 'class_number': 'A', 'sex': 'boy'}}
	])
	students_info.get_all_students()
	result = students_info.search_users(name='d')
	print(result)
	result = students_info.search_users(name='小')
	print(result)
	# 如果同学想用年龄字段模糊查询,
	# 需要把年龄改为str类型
	print('---------------')
	result = students_info.search_users(name='')
	print(result)

hosted with ❤ by GitHub