Python: how to iterate over files in a directory while adding new files until certain number is reached?

Question

How can I do the following in Python?

for file in os.listdir(directory):
    do sth
    output file to the folder
    if filenumber in the folder >=100:
        break

I think the first line for file in folder can find the newly created files.
Instead it just loop through the files that existed when the sript starts.
Any idea to make it work? Thanks.

Answer 1

os.listdir gives you a list of files and subdirectories in the given directory at the moment it is called. Any changes you make to the directory are not seen. You could keep rereading the directory

while True:
    files = os.listdir(directory)
    if len(files) >= 100: 
        break
    new_file = do_a_thing()
    open(new_file).write("foo")

Or just do the math once at the start

files = os.listdir(directory)
delta = 100 - len(files)
if delta > 0:
    for file in files[:delta]:
         ...