It seems like a bug to me, so I am not sure if this is correct place for this question but here it is.
I have declared a custom dataset something like:
from torch.utils.data import Dataset

class FaceLandmarksDataset(Dataset):
    """Face Landmarks dataset."""

    def __init__(self, csv_file, root_dir, transform=None):
        """
        Args:
            csv_file (string): Path to the csv file with annotations.
            root_dir (string): Directory with all the images.
            transform (callable, optional): Optional transform to be applied
                on a sample.
        """
        self.landmarks_frame = pd.read_csv(csv_file)
        self.root_dir = root_dir
        self.transform = transform

    def __len__(self):
        return len(self.landmarks_frame)

    def __getitem__(self, idx):
        if torch.is_tensor(idx):
            idx = idx.tolist()

        img_name = os.path.join(self.root_dir,
                                self.landmarks_frame.iloc[idx, 0])
        image = io.imread(img_name)
        landmarks = self.landmarks_frame.iloc[idx, 1:]
        landmarks = np.array([landmarks])
        landmarks = landmarks.astype('float').reshape(-1, 2)
        sample = {'image': image, 'landmarks': landmarks}

        if self.transform:
            sample = self.transform(sample)

        return sample

Now I declare an instance of this class:
val_percent=0.2
batch_size=1

dataset = FaceLandmarksDataset('file_path.csv', 'img_dir')
n_val = int(len(dataset) * val_percent)
n_train = len(dataset) - n_val
train, val = random_split(dataset, [n_train, n_val])
train.transform = transform(useAugmentations=True)
val.transform = transform(useAugmentations=False)


The code works but the transformation is not applied. However, if I declare with the transformation from the beginning like the following then it works fine.
dataset = FaceLandmarksDataset('file_path.csv', 'img_dir', transform(useAugmentations=True))
n_val = int(len(dataset) * val_percent)
n_train = len(dataset) - n_val
train, val = random_split(dataset, [n_train, n_val])

So how can I override a instance variable for the class of type Dataset and why is it on updating like it should?