执行导入的 function 本身时，嵌套 python 模块导入的问题

Question

I believe this question must have already been asked but I cannot find an explanation for my problem, sorry if it is a duplicate.

Folder
├── Generator.py
└── modules
    ├── Function1.py
    └── Subfunction.py

Generator.py imports Function1, and Function1 imports Subfunction. Function1 must be able to be run as a standalone program and as an imported module of Generator.py

It is not a problem itself, as I am using the if __ name__ == "__ main__": to recognize the call type.
But the program fails on importing Subfunction depending on the code I am executing.

# Generator.py
    import Function1

# Function1.py
    import Subfunction
    import modules.Subfunction

The first one works if I execute Function1.py, but it fails if I run Generator.py

The second one works if I execute Generator.py, but it fails if I run Function1.py

I thought imports and relative paths are related to the module where the code is placed, not from a perspective of the top-caller. I tried import.modules.Function1 and import.Function1 but the issue remains. Is there any elegant way to import Subfunction for both uses, or do I need to include import under if name == main or trap it in try/except ?

Edit: all code for @Bastien B

In this shape it works if I execute Function1.py itself. If I execute Generator.py, I get the ModuleNotFoundError: No module named 'Function1'

# Generator.py
    import Function1
    print(Function1.Function1_return)

# Function1.py
    def Function1_return():
        return Subfunction.Subfunction_return()
    import Subfunction
    if __name__ == '__main__':
        print(Function1_return())

# Subfunction.py
    def Subfunction_return():
        return "this is subfunction"

Answer 1

From what i can see your 'if name ...' is not the problem.

If you use a local venv this should work just fine:

generator.py

from Folder.modules.function1 import Function1_return
print(Function1_return())

Function1.py

from Folder.modules.Subfunction import Subfunction_return

def Function1_return():
    return Subfunction_return()

if __name__ == '__main__':
    print(Function1_return())

Subfunction.py

def Subfunction_return():
    return "this is subfunction"

Depending of your files structure you may have to tweak this a beat