CODEWITHSUNDEEP
pythoncaching
user46646
user46646

Reputation: 159401

Strange behavior after deleting *.pyc and rerunning .py script

I have three modules as:

one.py:

def abc():
    print "Heeeeeeeeeeeiiiiiioooooooooo"

two.py:

import one

def defg():
    one.abc()

three.py:

import os
from time import sleep

import two
two.defg()

sleep(20)


directory = os.listdir('.')

for filename in directory:
    if filename[-3:] == 'pyc':
        print '- ' + filename
        os.remove(filename)

I have three doubts.

When I run three.py for the first time one.pyc and two.pyc will be created. I can see it since I gave 20 sec delay. After executing the statement os.remove(filename), they get removed. Until here its fine.

Again without closing the IDLE as well as the script, I ran three.py. This time no .pyc file was created. Why is this so?

If I close IDLE as well as the script, .pyc will be created as before.

  1. Why the compiled code is not getting created again and again?

  2. Also, if I make a change in one.py it will not be shown if I run without closing the shells. I need a solution for this also.

  3. Third doubt is if the compiled code is getting deleted first time itself, then how the second run gives the same result without .pyc?

Upvotes: 1

Views: 2480

Answers (3)

Nathan Ross Powell
Nathan Ross Powell

Reputation: 512

The .pyc is not getting created again because there is a reference to your imported module in code. When it is re-run, this reference is used.

This is why the .pyc is not generated again, and also why the extra changes you make are not getting run.

You can either remove all references and call a garbage collect, or use the built in reload() function on the modules. e.g.:

reload(three)

Upvotes: 8

Mohammad Shahid Siddiqui
Mohammad Shahid Siddiqui

Reputation: 4160

Edit ~/.bashrc and add this shell function to it

$ cd ; pyclean

pyclean () {
        find . -type f -name "*.py[co]" -delete
        find . -type d -name "__pycache__" -delete
}

Upvotes: 1

mikl
mikl

Reputation: 24307

I think that IDLE is caching the bytecode within its own Python process, so it doesn't need to regenerate the it each time the file is run.

Upvotes: 1

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