in Python, how to overwrite the str for a module?

Question

When one types the name of a module and then hits return, one gets a string like below

import pandas as pd
pd

<module 'pandas' from '....'>

How can I overwrite this string for my own module ? (Please note that I am referring to a module, not to a class) For example adding a text below like

<module 'mymodule' from '....'>
my additional custom text

I tried to add this to mymodule:

def __str__():
   print('my additional custom text')

and also

def __str__():
   return 'my additional custom text'

def __repr__():
    print("my additional custom text")
    return "my additional custom text"

but nothing happens

Of course, if I type

mymodule.__str__()

I get 'my additional custom text'

https://www.digitalocean.com/community/tutorials/python-str-repr-functions ? but the main thing is probably to use return instead of print — Sir l33tname, Apr 13 '23 at 13:37
I would start with looking at `__name__` and `__spec__` and particularly `__str__` — JonSG, Apr 13 '23 at 13:41
Did you also dig into `__repr__` instead of `__str__` ? Depending from where you are typing those python commands, it may be the right redefinition to do. — PoneyUHC, Apr 13 '23 at 13:44
Possible relevant, though I think this was from the Python 2 days: https://stackoverflow.com/questions/1725515/can-a-python-module-have-a-repr — slothrop, Apr 13 '23 at 13:53

score 1 · Accepted Answer · answered Apr 13 '23 at 14:11

@JonSG was correct, it reads it from __spec__ - I found all the logic for it is in the importlib._bootstrap module.

This is how you'd modify the module name and path:

import sys

if __spec__ is not None:
    file_path = 'C:/other_file'
    name = 'new_name'

    __spec__.origin = file_path

    if name != __spec__.name:
        sys.modules[name] = sys.modules[__spec__.name]
        __spec__.name = name

When I import the file:

<module 'new_name' from 'C:/other_file'>

Changing the name actually requires editing sys.modules so be careful. Changing the path however looks completely fine.

What can be done is to leave the real path name, and append a string to it. I had actually hoped it was something less invasive to do. Thanks to everyone that helped clarify the issue — minivip, Apr 18 '23 at 05:56

score 1 · Answer 2 · answered Apr 13 '23 at 14:55

A short answer is: cannot do. Importlib puts the module's repr together with its name and origin properties. Check out the _module_repr_from_spec function implementation.

I believe subclassing ModuleSpec and overriding its attributes is also not a viable option, unless you decide to do without Importlib and somehow load modules by yourself.

in Python, how to overwrite the str for a module?

2 Answers2