Python 通过执行改变的脚本

Question

how can I write a script that it changes by execution? For example, two a have script exist from two row:

list = [1, 2, 3, 4, 5]
sliced_list = list[0:1]

Executing it, 2nd row should be:

sliced_list = list[1:2]

and then,

sliced_list = list[2:3]

I want to modify variable "sliced_list" everytime I run this file.

Answer 1

Generally this is not something you should ever want to do, since it is likely to result in non-deterministic behavior, and in the event of a bug its possible to completely overwrite your script and lose data.

If you want to change the date your script is operating on you should store it persistently in some fashion. This could be in a separate file somewhere or in an environment variable.

But to do what your asking you would need to open the script, copy the contents, and modify the content as you desire like this:

with open("/path/to/script.py", 'r+') as script:
    contents = script.read()

    # ... some string logic here

    # Point cursor to the beginning of the file
    # If the original contents were longing than the new contents
    # you'll have unwanted data at the end of the file.
    script.seek(0)
    script.write(contents)

Answer 2

You could save the start index into a file when you run the script. Then increment it and save it. Something like what is shown below.

import os
List=[1,2,3,4,5]
file=open('file.txt','r+')
start_index=int(file.read())
print(List[start_index:start_index+1])
file.close()
os.remove('file.txt')
file=open('file.txt','w')
file.write(str(start_index+1))
file.close()