Lightning no longer works with non-primitive types in hparams
🐛 Bug
I will often use things like a layer definition passed in, for things like changing from batch norm to group norm or using a custom layer. Now that lightning uses the hparams feature in tensor board it errors out with these in hparams.
Code sample
from pytorch_lightning.loggers import TensorBoardLogger
from argparse import Namespace
params = Namespace(foo = range(10))
logger = TensorBoardLogger(save_dir='.')
logger.log_hyperparams(params)

Expected behavior
Lightning should convert non primitive types to strings before passing to the summary writer. This worked fine when logging hparams as a text object
Environment
Pytorch 1.4
Ubuntu 16
pip install pytorch_lightning
Python 3.7