Question

I am trying to load code as a module and then reload the same module but different code programmatically in Python:

import imp

a = """
def test():
    print "Hello from a"
"""

b = """
def test():
    print "Hello from b"
"""


for code in [a, b]:
    with open('user.py', 'wb') as f:
        f.write(code)
    mod = imp.load_source('user', 'user.py')
    getattr(mod, "test")()

Expected output:

Hello from a
Hello from b

Actual output:

Hello from a
Hello from a

Obviously my understanding of how it works is not correct but I can’t seem to figure out my mistake.

The only way I could get it to work was if I deleted the generated .pyc file before I wrote the code in the file f. Is there a better way?

Answer 1

Probably not because the timestamp of your .pyc file (accurate to a second) will not be older than the timestamp for your newly written .py file; therefore imp will use the “current” .pyc file unless you delete it first.

Alternatively, you could try waiting for two seconds before reloading the module.