Python/list/file/loop/append-CodePudding

I have to open a file and loop through the list. Then I have to print the results and append/write certain lines to the same file. I want to be abale to run the code multiple times, but I do not want to append certain lines multiple times, but only once. The question is - how to append/write only once? Here is the code:

kitty = 500

requests = []

file = open("loan_requests.txt", "r ")

requests = file.readlines()

for item in requests:
    
    if int(item) < kitty and kitty > 0:
        kitty = kitty - int(item)
        loan = int(item)
        file.write("Request of {} paid in full.".format(loan))
        print(loan, "- Paid!")

        
    elif int(item) > kitty and kitty > 0:
            kitty = kitty - int(item)
            loan = int(item)   kitty
            file.write("Request of {} could not be paid in full.Partial payment of {} made.".format(item, loan))
            print(int(item), "request cannot be processed in full (Insufficient funds available). Amount paid:", loan)
            
            
    elif int(item) > kitty and kitty <= 0:
            file.write("Outstanding Request:{}".format(item))
            print("Request of", int(item), "is UNPAID!")

file.close()

I tried to use break method, but it doesn't help.

CodePudding user response：

Before writing to the file, check if the file already contains that line.

kitty = 500

requests = []

file = open("loan_requests.txt", "r ")

requests = file.readlines()

def write_new(file, line, requests):
    if line not in requests:
        file.write(line)

for item in requests:
    
    if int(item) < kitty and kitty > 0:
        kitty = kitty - int(item)
        loan = int(item)
        write_new(file, "Request of {} paid in full.\n".format(loan), requests)
        print(loan, "- Paid!")

    elif int(item) > kitty and kitty > 0:
        kitty = kitty - int(item)
        loan = int(item)   kitty
        write_new(file, "Request of {} could not be paid in full.Partial payment of {} made.\n".format(item, loan), requests)
        print(int(item), "request cannot be processed in full (Insufficient funds available). Amount paid:", loan)
            
    elif int(item) > kitty and kitty <= 0:
        write_new(file, "Outstanding Request:{}\n".format(item), requests)
        print("Request of", int(item), "is UNPAID!")

file.close()

CodePudding user response：

Converting what Barman suggests, let's start with helper function that will write or not depends on some flag:

SHOULD_WRITE = True
def maybe_write(file, message):
    if SHOULD_WRITE:
        file.write(message)

Now use that function instead of file.write:

# file.write("Request of {} paid in full.".format(loan))
maybe_write(file, f"Request of {loan} paid in full.")

Next time, change value of SHOULD_WRITE = False

BONUS: Do you know python has such fancy syntax?

if 0 < kitty < int(item):
    ...