python with使用

使用with 打开文件，不用手动关闭文件。自动关闭文件

def read_file(file_path: str):with open(file_path, 'r', encoding='utf-8') as file:content = file.read()print(content)def main():file_path = "hello.txt"read_file(file_path)if __name__ == '__main__':main()

　自定义python with上下文

class MyContextManager:def __enter__(self):print('进入上下文')return 'hello python'def __exit__(self, exc_type, exc_val, exc_tb):print('离开上下文')if exc_type:print(f'捕获异常:{exc_val}')return Trueif __name__ == '__main__':with MyContextManager() as my_context_manager:print(my_context_manager)raise ValueError('测试异常')