Python truncate lines as they are read

Question

I have an application that reads lines from a file and runs its magic on each line as it is read. Once the line is read and properly processed, I would like to delete the li

Answer 1

This is what I use for file based queues. It returns the first line and rewrites the file with the rest. When it's done it returns None:

def pop_a_text_line(filename):
    with open(filename,'r') as f:
        S = f.readlines()
    if len(S) > 0:
        pop = S[0]
        with open(filename,'w') as f:
            f.writelines(S[1:])
    else:
        pop = None
    return pop