fix boolean argparse (#1571)

* fix boolean argparse #1570

* update change log

Author: fschlatt

CHANGELOG.md

@@ -62,6 +62,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 - Fixed a bug that caused the `callbacks` Trainer argument to reference a global variable ([#1534](https://github.com/PyTorchLightning/pytorch-lightning/pull/1534)).
 
+- Fixed a bug that set all boolean CLI arguments from Trainer.add_argparse_args always to True ([#1570](https://github.com/PyTorchLightning/pytorch-lightning/issues/1570))
 
 ## [0.7.3] - 2020-04-09
 

pytorch_lightning/trainer/trainer.py

@@ -603,7 +603,7 @@ def add_argparse_args(cls, parent_parser: ArgumentParser) -> ArgumentParser:
         for arg, arg_types, arg_default in (at for at in cls.get_init_arguments_and_types()
                                             if at[0] not in depr_arg_names):
             for allowed_type in (at for at in allowed_types if at in arg_types):
-                if isinstance(allowed_type, bool):
+                if allowed_type is bool:
                     def allowed_type(x):
                         return bool(distutils.util.strtobool(x))
                 parser.add_argument(