Prepare Namespace package (#1543)

* Update __init__.py

* Update setup.py

pytorch_lightning/__init__.py

@@ -60,4 +60,13 @@ else:
         'Callback',
         'data_loader'
     ]
+
+    # necessary for regular bolts imports. Skip exception since bolts is not always installed
+    try:
+        from pytorch_lightning import bolts
+    except ImportError:
+        pass
     # __call__ = __all__
+
+# for compatibility with namespace packages
+__import__('pkg_resources').declare_namespace(__name__)

setup.py

@@ -3,7 +3,7 @@
 import os
 from io import open
 # Always prefer setuptools over distutils
-from setuptools import setup, find_packages
+from setuptools import setup, find_namespace_packages
 
 try:
     import builtins
@@ -57,7 +57,7 @@ setup(
     url=pytorch_lightning.__homepage__,
     download_url='https://github.com/PyTorchLightning/pytorch-lightning',
     license=pytorch_lightning.__license__,
-    packages=find_packages(exclude=['tests', 'tests/*', 'benchmarks']),
+    packages=find_namespace_packages(exclude=['tests', 'tests/*', 'benchmarks']),
 
     long_description=load_long_describtion(),
     long_description_content_type='text/markdown',