lightning/pytorch_lightning/overrides/base.py

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# Copyright The PyTorch Lightning team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from typing import Any
import torch
from pytorch_lightning.core.lightning import LightningModule
from pytorch_lightning.trainer.states import RunningStage
from pytorch_lightning.utilities.warnings import WarningCache
warning_cache = WarningCache()
class _LightningModuleWrapperBase(torch.nn.Module):
def __init__(self, pl_module: LightningModule):
"""
Wraps the user's LightningModule and redirects the forward call to the appropriate
method, either ``training_step``, ``validation_step`` or ``test_step``.
If the LightningModule is in none of the states `training`, `testing` or `validation`,
the inputs will be redirected to the
:meth:`~pytorch_lightning.core.lightning.LightningModule.predict` method.
Inheriting classes may also modify the inputs or outputs of forward.
Args:
pl_module: the model to wrap
"""
super().__init__()
self.module = pl_module
def forward(self, *inputs, **kwargs):
running_stage = self.module.running_stage
if running_stage == RunningStage.TRAINING:
output = self.module.training_step(*inputs, **kwargs)
warn_if_output_is_none(output, "training_step")
elif running_stage == RunningStage.TESTING:
output = self.module.test_step(*inputs, **kwargs)
warn_if_output_is_none(output, "test_step")
elif running_stage == RunningStage.EVALUATING:
output = self.module.validation_step(*inputs, **kwargs)
warn_if_output_is_none(output, "validation_step")
else:
output = self.module.predict(*inputs, **kwargs)
return output
def warn_if_output_is_none(output: Any, method_name: str) -> None:
""" Warns user about which method returned None. """
if output is None:
warning_cache.warn(f'Your {method_name} returned None. Did you forget to return an output?')