设计模式-C++

观测者模型

https://cloud.tencent.com/developer/article/1901837#:~:text=观察者模式（Observer ,Pattern%EF%BC%89%E4%B8%BB%E8%A6%81%E8%A7%A3%E5%86%B3%E7%9A%84%E6%98%AF%E5%BD%93%E5%AF%B9%E8%B1%A1%E9%97%B4%E5%AD%98%E5%9C%A8%E4%B8%80%E5%AF%B9%E5%A4%9A%E5%85%B3%E7%B3%BB%E6%97%B6%E5%BD%93%E4%B8%80%E4%B8%AA%E5%AF%B9%E8%B1%A1%E8%A2%AB%E4%BF%AE%E6%94%B9%EF%BC%8C%E4%BC%9A%E8%87%AA%E5%8A%A8%E9%80%9A%E7%9F%A5%E4%BE%9D%E8%B5%96%E5%AE%83%E7%9A%84%E5%85%B6%E5%AE%83%E5%AF%B9%E8%B1%A1%E3%80%82