在没有初始化的情况下将计数器存储在搁置文件中 - Python

Question

The program generates a variable guest n with n incrementing for each guest. I want the program to start at the last guest number whenever it runs.

I can only get the program to work by initializing shelf_file["count"] , if I don't I get a key error.

shelf_file = shelve.open("mydata")

shelf_file["count"] = 0   #I want to get rid of this line

shelf_file["count"] += 1
guest_id = "guest" + str(shelf_file["count"])

Thanks.

Answer 1

Solved with shelf_file.setdefault("count", 1)

Thanks @Jkdc for pointing me in the right direction.

For some reason shelf_file kept storing "None" until I deleted the files in the directory.