import module within loop

Question

I have one file, let's call it foo.py. It does a couple of things, including sending some data over a serial port and emailing the response that comes back.

I have another file, which looks something like this:

iteration = 0
while True:
    iteration += 1
    // do some stuff here every time
    if iteration%5 == 0:
        import foo
    time.sleep (100)

I'm aware there are some broader problems here with the elegance (or lack thereof) of an independent counter, but putting that aside - the serial transmission / email only works the first time it's triggered. Subsequent loops at a multiple of 5 (which will trigger the modulo 5 == 0) do nothing.

Does my imported version of foo.py get cached, and avoid triggering on subsequent runs? If yes, how else can I call that code repeatedly from within my looping script? Should I just include it inline?

Thanks for any tips!

Basically. Put your code from `foo` into a function, your import at the start of the file, and call `foo.name_of_function()` — NightShadeQueen, Jul 02 '15 at 01:10
Thanks for the question VenomFangs. NightShadeQueen is correct - it's just a block of code I wanted to re-execute multiple times. Makes more sense for it to live in a function. — penitent_tangent, Jul 02 '15 at 01:27

score 7 · Accepted Answer · edited May 23 '17 at 12:21

7

If you have access to foo.py, you should wrap whatever you want to run in foo.py in a function. Then, just import foo once and call the function foo.func() in the loop.

See this for an explanation of why repeated imports does not run the code in the file.

edited May 23 '17 at 12:21

Community

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1

answered Jul 02 '15 at 01:11

James

1,198
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Oh of course - this makes complete sense. Thank you! – penitent_tangent Jul 02 '15 at 01:28

koffein · Answer 2 · 2015-07-02T01:21:08.687

2

You can replace import foo with

if 'foo' in dir(): # if it has already been imported
    reload(foo)
else:
    import foo

Not quite sure, but this should work. Edit: Now I am sure.

edited Jul 02 '15 at 01:21

answered Jul 02 '15 at 01:10

koffein

1,792
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Yes, it should work, but ___please___ don't do this. The `reload()` function should really only be used during development, when you're working in an interactive interpreter and you need to reload a module that you've modified. See [the docs for reload()](https://docs.python.org/2/library/functions.html#reload). Note that in Python 3, `reload()` is _not_ a built-in, you have to import it from [imp](https://docs.python.org/3/library/imp.html#imp.reload) or [importlib](https://docs.python.org/3/library/importlib.html#importlib.reload). – PM 2Ring Jul 02 '15 at 01:22
@PM2Ring Yes, you are right, but I actually think the OP is aware of that. – koffein Jul 02 '15 at 01:25
Perfect, thanks. I wasn't aware this is an option and it's good to know too :) – penitent_tangent Jul 02 '15 at 01:28

import module within loop

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