794 lines
15 KiB
Markdown
794 lines
15 KiB
Markdown
# python高级
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## 闭包
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> 函数1嵌套函数2, 函数1返回函数2, 函数2使用了外部的变量
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> 用处: 防止全局变量被外部修改
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```python
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def outer_function(x):
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def inner_function(y):
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return x + y
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return inner_function
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# 创建一个闭包
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closure = outer_function(10)
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# 闭包被使用
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result = closure(5)
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print(result) # 输出 15
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```
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* 如何要修改外部函数变量的值, 需要用nonlocal修饰
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```python
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def outer_function():
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x = 10 # 外部函数中定义的变量
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def inner_function():
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nonlocal x # 使用 nonlocal 关键字声明 x 是外部函数中的变量
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x += 5
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print("内部函数中修改后的 x:", x)
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inner_function()
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print("外部函数中的 x:", x)
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# 调用外部函数
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outer_function()
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`````
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其他: global修饰
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```python
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global_variable = 10 # 全局变量
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def modify_global_variable():
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global global_variable # 使用 global 关键字声明在函数内部使用全局变量
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global_variable += 5
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modify_global_variable()
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print(global_variable) # 输出 15，因为函数内部修改了全局变量的值
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```
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## 装饰器
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> 在不破坏目标函数的功能前提下, 为目标函数添加功能
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> 实际就是用闭包实现的
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```python
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def my_decorator(func):
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def wrapper():
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print("在调用被装饰函数之前的操作")
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func() # 调用原始函数
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print("在调用被装饰函数之后的操作")
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return wrapper # 返回新的函数
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@my_decorator # 使用装饰器语法
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def say_hello():
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print("Hello!")
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# 调用被装饰后的函数
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say_hello()
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```
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其实是语法糖
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```python
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def my_decorator(func):
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def wrapper():
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print("在调用被装饰函数之前的操作")
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func() # 调用原始函数
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print("在调用被装饰函数之后的操作")
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return wrapper # 返回新的函数
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def say_hello():
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print("Hello!")
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fn = my_decorator(say_hello)
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fn()
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```
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* 把字典转化成对象
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```python
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from dataclasses import dataclass
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@dataclass
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class Torrent:
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name: str
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size: int
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# 定义一个字典
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torrent_dict = {
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'name': 'example_torrent',
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'size': 1024
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}
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# 使用字典初始化对象
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torrent_obj = Torrent(**torrent_dict)
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# 现在你可以访问对象的属性
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print(torrent_obj.name)
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print(torrent_obj.size)
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```
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## 设计模式
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> 单例, 工厂, 建造者, 责任链, 状态, 备忘录, 解释器, 访问者, 观察者, 中介, 模板, 代理模式
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### 单例模式
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> 某些场景下，我们需要一个类无论获取多少次类对象，都仅仅提供一个具体的实例, 以节省创建类对象的开销和内存开销
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> 定义: 保证一个类只有一个实例,并提供一个访问它的全局访问点
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简单案例:
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```python
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class Tools:
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pass
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str_tools = Tools()
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```
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```python
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from test import str_tools
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s1 = str_tools()
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s2 = str_tools()
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print(s1)
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print(s2)
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# s1 和 s2 是同一个对象
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```
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案例2:
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```python
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def singleton(cls):
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instances = {} # 存储实例的字典
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def get_instance(*args, **kwargs):
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if cls not in instances:
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# 如果实例不存在，创建一个新的实例
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instances[cls] = cls(*args, **kwargs)
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return instances[cls]
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return get_instance
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@singleton
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class MyClass:
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def __init__(self, name):
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self.name = name
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# 创建两个实例，实际上是同一个实例
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obj1 = MyClass("Instance 1")
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obj2 = MyClass("Instance 2")
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# 输出实例的名称
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print(obj1.name) # 输出 "Instance 1"
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print(obj2.name) # 输出 "Instance 1"，因为实际上是同一个实例
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```
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### 工厂模式
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> 大量创建对象时, 提供一个统一的入口
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> 当发生变化的时候, 仅修改工厂类的创建方法
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```python
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class Dog:
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def speak(self):
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return "汪汪汪!"
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class Cat:
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def speak(self):
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return "喵喵喵!"
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class AnimalFactory:
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def create_animal(self, animal_type):
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if animal_type == "Dog":
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return Dog()
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elif animal_type == "Cat":
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return Cat()
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else:
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raise ValueError("不支持的动物类型")
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# 使用工厂创建对象
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factory = AnimalFactory()
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dog = factory.create_animal("Dog")
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cat = factory.create_animal("Cat")
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# 调用对象的方法
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print(dog.speak()) # 输出 "汪汪汪!"
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print(cat.speak()) # 输出 "喵喵喵!"
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```
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## 多线程
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```python
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import threading
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thread_obj = threading.Thread([group [, target [, name [, args [, kwargs]]]]])
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# group 暂时无用, 未来功能的预留参数
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# target 执行的任务目标名
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# args 以元组方式传参
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# kwargs 以字典方式传参
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# name 线程名, 一般不用设置
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thread_obj.start()
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```
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## socket
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需要服务端+客户端
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### 服务端
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```python
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# 服务端
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# 1. 创建socket对象
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import socket
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socket_server = socket.socket()
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# 2. 服务端绑定ip和端口
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socket_server.bind(('0.0.0.0', 8888))
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# 3. 监听端口, 括号内为连接数量, 不填会自动设置一个合理的值
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socket_server.listen(5)
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# 4. 接受客户端连接
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client, addr = socket_server.accept()
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print('连接地址:', addr)
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# accept()方法会阻塞, 直到有客户端连接才会往下执行Í
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# accept()返回二元元组, 可以用两个变量接收
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# 5. recv接收
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while True:
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data = client.recv(1024).decode("UTF-8")
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# recv()参数为缓存区大小, 设置为1024, 代表缓存区为1024字节
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# recv()返回值是字节数组(bytes对象), 需要decode()方法将字节数组转为字符串
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print(f"接收的数据: {data}")
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if data == "exit":
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break
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# 6. send发送数据
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client.send(f"已接收数据: {data}".encode("UTF-8"))
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# 7. 关闭连接
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client.close()
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socket_server.close()
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# 客户端可以先通过 https://github.com/nicedayzhu/netAssist/releases 测试
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```
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### 客户端
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```python
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# 1. 创建服务
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import socket
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socket_client = socket.socket()
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# 2.建立连接
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socket_client.connect(('127.0.0.1', 8888))
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while True:
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msg = input("请输入要发送的数据: ")
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# 3. 发消息
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socket_client.send(msg.encode("UTF-8"))
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if msg == "exit":
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break
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# 4. 接收消息
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# recv 是阻塞式的
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data = socket_client.recv(1024).decode("UTF-8")
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print(f"接收的数据: {data}")
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# 5. 关闭
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socket_client.close()
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```
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===服务端先接收再发送, 服务端先发送再接收===
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## 异步
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### httpx
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### asyncio
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## with as
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```python
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with <expression> as <variable>:
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# 代码块
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```
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* `<expression>`：通常是一个上下文管理器对象，实现了`__enter__`和`__exit__`方法。
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* `<variable>`：可选，用于存储由上下文管理器返回的对象。
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`with`语句在进入和退出代码块时分别调用对象的`__enter__`和`__exit__`方法，这样可以确保资源在合适的时候被正确获取和释放。例如，在处理文件时：
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```python
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with open('file.txt', 'r') as file:
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content = file.read()
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# 在这里使用文件内容进行操作
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# 在此处退出上下文，文件会被正确关闭
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```
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## 列表推导式
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```python
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[expression for item in iterable if condition]
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```
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* expression：对可迭代对象中每个元素进行操作或处理的表达式。
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* item：可迭代对象中的每个元素。
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* iterable：用于迭代的对象，如列表、元组、集合等。
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* condition：可选的条件，用于过滤元素。如果条件为真，元素将包含在最终的列表中
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## 设置pip 镜像
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```sh
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mkdir ~/.pip
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vim ~/.pip/pip.conf
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===
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[global]
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trusted-host = mirrors.aliyun.com
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index-url = http://mirrors.aliyun.com/pypi/simple
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===
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```
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### 生成`requirements.txt`
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```python
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pip install pipreqs
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pipreqs .
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```
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### 引用
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```txt
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-r demo/requirements.txt
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```
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## 版本管理和虚拟环境
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### pyenv 版本管理
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```sh
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brew install pyenv
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# homebrew安装的python环境变量可以屏蔽了
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# 比教程多了 $PYENV_ROOT/shims
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echo 'export PYENV_ROOT="$HOME/.pyenv"' >> ~/.zshrc
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echo '[[ -d $PYENV_ROOT/bin ]] && export PATH="$PYENV_ROOT/bin:$PYENV_ROOT/shims:$PATH"' >> ~/.zshrc
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echo 'eval "$(pyenv init -)"' >> ~/.zshrc
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pyenv install -l
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pyenv install 3.10.4
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pyenv uninstall <versions>
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pyenv global 3.10 # 设置全局
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pyenv global # 查看全局
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pyenv shell <version> # 设置当前shell
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pyenv local <version> # 设置当前目录 生成 .python-version 文件
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pyenv local # 查看当前目录, 读取 .python-version 文件
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# 查看已安装的版本
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pyenv versions
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# 查看当前目录的版本
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pyenv version
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```
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### venv 自带虚拟环境
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venv 是python 3.3后官方自带的, 在这之前就有第三方virtualenv
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缺点: 只能使用当前系统已经安装好的python，无法使用其他版本的python环境
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```sh
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# 添加虚拟环境
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python3 -m venv .venv
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# 激活
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source .venv/bin/activate
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# 正常使用pip
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pip install -r requirements.txt
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# 取消激活
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deactivate
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```
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* vscode 自动激活
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`"python.terminal.activateEnvInCurrentTerminal": true`
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cmd+shift+p : python create env
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看vscode下方状态栏是否显示env和python版本
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* zsh 钩子自动激活
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```sh
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vim ~/.zshrc
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# 定义 chpwd 钩子
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chpwd_hook() {
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# 检查当前目录中是否存在 venv 或 .venv 目录
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if [ -d "venv" ]; then
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# 如果存在 venv 目录，则激活虚拟环境
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source venv/bin/activate
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echo '激活python环境'
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elif [ -d ".venv" ]; then
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# 如果存在 .venv 目录，则激活虚拟环境
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source .venv/bin/activate
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echo '激活python环境'
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fi
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}
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# 将 chpwd_hook 设置为 chpwd 钩子
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chpwd_functions+=(chpwd_hook)
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```
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* direnv
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https://direnv.net/docs/hook.html
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```sh
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brew install direnv
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# 添加到~/.zshrc
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eval "$(direnv hook zsh)"
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# 关闭提示
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export DIRENV_LOG_FORMAT=
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# 在项目下新建.envrc
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echo 'source $PWD/.venv/bin/activate' > .envrc
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# 允许当项目下加载配置
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direnv allow
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```
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常见函数:
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https://direnv.net/man/direnv-stdlib.1.html
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`PATH_add bin`
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### uv 包管理器
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> 用来代替 pip pip-tools virtualenv 命令
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> 有全局缓存
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```sh
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brew install uv
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# 创建虚拟环境
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uv venv
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source .venv/bin/activate
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# 或者不激活直接 uv run xx.py
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uv pip install xxx
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uv pip install -r requirements.txt
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uv pip sync requirements.txt
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# 生成依赖列表
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uv pip freeze > requirements.txt
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# 指定系统中某个版本的python
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PYENV_VERSION=3.12.2 uv venv
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--python 参数可以指定pyton路径
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```
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* 设置镜像
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```sh
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export UV_DEFAULT_INDEX="http://mirrors.aliyun.com/pypi/simple"
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```
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* macos 使用硬链接
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```sh
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export UV_LINK_MODE="hardlink"
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```
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### rye 虚拟环境和包管理
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包管理可以使用 `uv`
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### miniconda/miniforge
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适合公司使用, vscode不会自动切换环境
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miniforge是社区免费版, miniconda是公司产品
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```sh
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brew install miniforge
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# 设置镜像源
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conda config --add channels https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free/
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conda config --add channels https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/main/
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conda config --add channels https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/pytorch/
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conda config --add channels https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge/
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conda config --set show_channel_urls yes
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conda config --show channels
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conda update --all
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# 默认创建了一个base的环境
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# 用Python 3.9创建一个名为 f0x 的虚拟环境
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conda create -n f0x python=3.9
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# 查看所有环境
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conda info --envs
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conda env list
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# 激活虚拟环境
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conda activate f0x
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# 安装库
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conda install jupyter
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```
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### poetry 虚拟环境和包管理
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https://blog.kyomind.tw/python-poetry/
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||
https://python-poetry.org/docs/main/configuration/
|
||
|
||
```sh
|
||
curl -sSL https://install.python-poetry.org | python3 -
|
||
# 安装路径 $HOME/.local/bin
|
||
# poetry 要安装在单独的虚拟环境中, 因为它自己就带一堆包, 并且会依赖特定版本的python
|
||
# 卸载
|
||
curl -sSL https://install.python-poetry.org | POETRY_UNINSTALL=1 python3 -
|
||
|
||
vim ~/.zshrc
|
||
===
|
||
alias p="poetry"
|
||
===
|
||
source ~/.zshrc
|
||
|
||
# 初始化
|
||
poetry init
|
||
|
||
# 安装环境当前工作目录下
|
||
poetry config virtualenvs.in-project true
|
||
# 查看配置
|
||
poetry config --list
|
||
|
||
poetry env use python
|
||
# poetry env use python3
|
||
# poetry env use python3.8
|
||
# poetry env use 3.8
|
||
poetry env remove python
|
||
|
||
# 进入虚拟环境
|
||
poetry shell
|
||
# 退出
|
||
exit
|
||
|
||
# 相当于pip list
|
||
poetry show
|
||
poetry show --tree
|
||
poetry show 模块名 --tree
|
||
|
||
# 不进入shell也可以安装
|
||
poetry add 模块名
|
||
poetry remove 模块名
|
||
# 安装到开发环境
|
||
poetry add 模块名 --group dev
|
||
|
||
# 更新所有模块
|
||
poetry update
|
||
# 更新指定模块
|
||
poetry update 模块名
|
||
|
||
# 手动修改pyproject.toml后不会自动更新lock, 需要执行
|
||
poetry lock
|
||
poetry install --sync
|
||
|
||
# 导入requirements.txt
|
||
cat requirements.txt | xargs poetry add
|
||
|
||
# 导出requirements
|
||
poetry export -f requirements.txt -o requirements.txt --without-hashes
|
||
|
||
# 按照 pyproject.toml 安装
|
||
poetry install
|
||
|
||
# 不进入环境执行运行
|
||
poetry run python3 main.py
|
||
|
||
# 更多指令
|
||
poetry list
|
||
|
||
# vscode 使用
|
||
poetry env info
|
||
poetry env info --path
|
||
# 手动指定python路径
|
||
```
|
||
|
||
## json
|
||
|
||
```python
|
||
# 内置模块 json
|
||
import json
|
||
|
||
data = [{"name":"张三", "age":18, "gender":"男"}]
|
||
|
||
# py数据转json
|
||
data = json.dumps(data)
|
||
print(data)
|
||
print(type(data))
|
||
|
||
# 中文变乱码
|
||
data = json.dumps(data, ensure_ascii=False)
|
||
print(data)
|
||
print(type(data))
|
||
|
||
# json转py数据
|
||
data = json.loads(data)
|
||
print(data)
|
||
print(type(data))
|
||
```
|
||
|
||
## 三目运算符
|
||
|
||
```python
|
||
x if condition else y
|
||
|
||
# 示例
|
||
|
||
x = 5
|
||
result = "Even" if x % 2 == 0 else "Odd"
|
||
print(result)
|
||
```
|
||
|
||
## 逻辑短路
|
||
|
||
```python
|
||
# and 运算符的逻辑短路
|
||
result_and = False and some_function() # some_function() 不会被调用
|
||
|
||
# or 运算符的逻辑短路
|
||
result_or = True or some_function() # some_function() 不会被调用
|
||
|
||
```
|
||
|
||
## **pycache**
|
||
|
||
python编译成字节码的产物, 直接vscode和gitignore忽略掉
|
||
|
||
## 锁
|
||
|
||
```python
|
||
import threading
|
||
|
||
# 创建一个锁
|
||
lock = threading.Lock()
|
||
|
||
# 使用锁来保护共享资源
|
||
shared_resource = 0
|
||
|
||
def update_shared_resource():
|
||
global shared_resource
|
||
with lock:
|
||
shared_resource += 1
|
||
|
||
# 创建多个线程来同时更新共享资源
|
||
threads = []
|
||
for _ in range(5):
|
||
t = threading.Thread(target=update_shared_resource)
|
||
threads.append(t)
|
||
t.start()
|
||
|
||
# 等待所有线程执行完毕
|
||
for t in threads:
|
||
t.join()
|
||
|
||
print(shared_resource) # 应该输出 5
|
||
```
|
||
|
||
* 装饰器写法
|
||
|
||
```python
|
||
def locked(func):
|
||
def wrapper(*args, **kwargs):
|
||
with lock:
|
||
return func(*args, **kwargs)
|
||
|
||
return wrapper
|
||
```
|
||
|
||
## 代码检查工具
|
||
|
||
* `ruff`
|
||
|
||
```sh
|
||
ruff src
|
||
# 递归检查
|
||
ruff src -- --recursive
|
||
# 修复
|
||
ruff src -- --recursive --fix
|
||
```
|
||
|
||
vscode 有 ruff 插件
|
||
|
||
* blank
|
||
|
||
```sh
|
||
black --check src
|
||
black src
|
||
```
|
||
|
||
## 测试
|
||
|
||
* pytest
|
||
|
||
```python
|
||
# 在src目录下创建test目录
|
||
# 在test目录下创建 __init__.py
|
||
# 测试脚本文件名 test_xxx.py, test_开头
|
||
from module.xxxx import xxxxx
|
||
|
||
def test_xxx():
|
||
# 使用assert断言
|
||
assert A == B
|
||
```
|
||
|
||
测试
|
||
|
||
```sh
|
||
cd src
|
||
pytest test
|
||
|
||
# 需要显示print
|
||
pytest -s test
|
||
```
|
||
|
||
### 进度条
|
||
|
||
```python
|
||
x = 10000
|
||
for i in range(x):
|
||
for j in range(x):
|
||
k = j * i
|
||
print(f"{i + 1} / {x}", end="\r")
|
||
print("\n完成!")
|
||
```
|
||
|
||
`end="\r"`表示每次输出后都不换行
|
||
|
||
第三方库:
|
||
|
||
* tqdm
|
||
* progress
|
||
|
||
## python vscode调试
|
||
|
||
```json
|
||
{
|
||
"version": "0.2.0",
|
||
"configurations": [
|
||
{
|
||
"name": "Python: Main",
|
||
"type": "python",
|
||
"request": "launch",
|
||
"program": "${workspaceFolder}/main.py", // main.py 的路径
|
||
"console": "integratedTerminal",
|
||
"justMyCode": false, // 设置为 false 以允许在子模块中设置断点
|
||
"env": {
|
||
// 在这里添加环境变量（如果需要）
|
||
}
|
||
}
|
||
]
|
||
}
|
||
|
||
``` |