I have a problem overriding the method where from...import
statement is used. Some example to illustrate the problem:
# a.py module def print_message(msg): print(msg) # b.py module from a import print_message def execute(): print_message("Hello") # c.py module which will be executed import b b.execute()
I'd like to override print_message(msg)
method without changing code in a or b module. I tried in many ways but from...import
imports the original method. When I changed the code to
import a a.print_message
then I see my change.
Could you suggest how to solve this problem?
------------------ Update ------------------
I tried to do that like below e.g.:
# c.py module import b import a import sys def new_print_message(msg): print("New content") module = sys.modules["a"] module.print_message = new_print_message sys.module["a"] = module
But this is not working where I'm using for...import
statement. Is working only for import a but as I wrote I don't want change code in b.py and a.py modules.
The from.. import statement allows you to import specific functions/variables from a module instead of importing everything. In the previous example, when you imported calculation into module_test.py , both the add() and sub() functions were imported.
So there's four different ways to import: Import the whole module using its original name: pycon import random. Import specific things from the module: pycon from random import choice, randint. Import the whole module and rename it, usually using a shorter variable name: pycon import pandas as pd.
When a module is first imported, Python searches for the module and if found, it creates a module object 1, initializing it. If the named module cannot be found, a ModuleNotFoundError is raised. Python implements various strategies to search for the named module when the import machinery is invoked.
With your a
and b
modules untouched you could try implementing c
as follows:
import a def _new_print_message(message): print "NEW:", message a.print_message = _new_print_message import b b.execute()
You have to first import a
, then override the function and then import b
so that it would use the a
module that is already imported (and changed).
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