custom_val.py

import torch, torch.nn as nn

class LowlevelModule(nn.Module):
    def __init__(self, custom_val):
        super().__init__()
        self.custom_val = custom_val

    def print_custom_val(self):
        print(self.custom_val.item())

class TopModel(nn.Module):
    def __init__(self):
        super().__init__()
        self.custom_val = torch.tensor([5.])
        self.m1 = LowlevelModule(self.custom_val)
        self.m2 = LowlevelModule(self.custom_val)

    def print_lowlevelvals(self):
        self.m1.print_custom_val()
        self.m2.print_custom_val()

    def forward(self): pass

if __name__ == '__main__':
    m = TopModel()
    m.print_lowlevelvals()

    # set new val
    m.custom_val[0] = 10.
    m.print_lowlevelvals()