How to save session data (Python)

Question

Say there is some code I wrote, and someone else uses, and inputs their name, and does other stuff the code has.

name = input('What is your name? ')
money = 5
#There is more stuff, but this is just an example.

How would I be able to save that information, say, to a text file to be recalled at a later time to continue in that session. Like a save point in a video game.

Answer 1

You can write the information to a text file. For example:

mytext.txt

(empty)

myfile.py

name = input('What is your name? ')
... 
with open('mytext.txt', 'w') as mytextfile:
    mytextfile.write(name)
    # Now mytext.txt will contain the name.

Then to access it again:

with open('mytext.txt') as mytextfile:
    the_original_name = mytextfile.read()

print the_original_name
# Whatever name was inputted will be printed.

Answer 2

Going with @Justin's comment, here is how I would save and read the session each time:

import cPickle as pickle

def WriteProgress(filepath, progress):
    with open(filepath, 'w') as logger:
        pickle.dump(progress, logger)
        logger.close()

def GetProgress(filepath):
    with open(filepath, 'r') as logger:
        progress = pickle.load(logger)
        logger.close()
    return progress

WriteProgress('SaveSessionFile', {'name':'Nigel', 'age': 20, 'school': 'school name'})
print GetProgress('SaveSessionFile')

{'age': 20, 'name': 'Nigel', 'school': 'school name'}

This way, when you read the file again, you can have all the varaibles you declared before and start from where you left off.

Remember that since your program uses pickle module to read and write session information, tampering with the file after it has been written to can cause unforeseen outcomes; so be careful that it is only the program writing to and reading from that file

Answer 3

You may be searching for a generalized mechanism that makes saving and restoring the wanted information somehow more easily. This is called persistence as the term in programming. However, it is not automatic. There are techniques how to implement it. The more complex and specific the implemented system is, the more specific the mechanism can be.

For simple cases, the explicit storing the data into a file is just fine. As Smac89 has shown in https://stackoverflow.com/a/18309156/1346705, the pickle module is a standard way how to save the status of whole Python objects. However, it is not neccessarily what you always need.

Update: The following code shows the principle. It should be enhanced for the real usage (i.e. should never be used this way, only in tutorial).

#!python3

fname = 'myfile.txt'

def saveInfo(fname, name, money):
    with open(fname, 'w', encoding='utf-8') as f:
        f.write('{}\n'.format(name))
        f.write('{}\n'.format(money))  # automatically converted to string

def loadInfo(fname):
    # WARNING: The code expect a fixed structure of the file.
    #   
    # This is just for tutorial. It should never be done this way
    # in production code.'''
    with open(fname, 'r', encoding='utf-8') as f:
        name = f.readline().rstrip()   # rstrip() is an easy way to remove \n
        money = int(f.readline())      # must be explicitly converted to int
    return name, money              


name = input('What is your name? ')
money = 5
print(name, money)

# Save it for future.
saveInfo(fname, name, money)

# Let's change it explicitly to see another content.
name = 'Nemo'
money = 100
print(name, money)

# Restore the original values.
name, money = loadInfo(fname)
print(name, money)