Python if-else 困惑

Question

是否有更简洁的方法来创建 msg？对于每个事件(Ping、Pull request、Issue、Issue comment、Repo、Create、Delete、Pull requset requset、Push、Commit comment)是否有一个 if 子句来检查事件并根据其操作创建消息。

    data = request.json
    event = request.headers['X-Github-Event']
    msg = ""

    ...

   # Pull request
   elif event == "pull_request":
       if data['action'] == "opened":
           msg = PullRequest(data).opened()
       elif data['action'] == "closed":
           msg = PullRequest(data).closed()
       elif data['action'] == "assigned":
           msg = PullRequest(data).assigned()

   # Issue
   elif event == "issues":
        if data['action'] == "opened":
            msg = Issue(data).opened()
        elif data['action'] == "reopened":
            msg = Issue(data).reopened()
        elif data['action'] == "closed":
            msg = Issue(data).closed()
        elif data['action'] == "labeled":
            msg = Issue(data).labeled()
        elif data['action'] == "assigned":
            msg = Issue(data).assigned()
    ...

Answer 1

动态地这样做怎么样，例如

getattr(PullRequest(data), data['action'], lambda:None)()

总结

elif event == "pull_request":
    getattr(PullRequest(data), data['action'], lambda:None)()
elif event == "issues":
    getattr(Issue(data), data['action'], lambda:None)()

lambda:None 背后的想法是，如果 data['action'] 实际上不是 PullRequest(数据) 或 问题(数据)。

---

或者如果你不喜欢 if-else 语句，比如

callables = {
    "pull_request":PullRequest,
    "issues":Issue,
}

getattr(callables[event](data), data['action'], lambda:None)()