Fix circular import issues

Author: Dominik Gresch

setup.py

@@ -1,10 +1,7 @@
 """Usage: pip install ."""
 
 import re
-try:
-    from setuptools import setup
-except ImportError:
-    from distutils.core import setup
+from setuptools import setup, find_packages
 
 import sys
 if sys.version_info < (3, 5):
@@ -56,6 +53,7 @@
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
         'Intended Audience :: Science/Research',
         'Topic :: Scientific/Engineering :: Physics',
         'Development Status :: 5 - Production/Stable'
@@ -65,8 +63,5 @@
         'topology', 'topological', 'invariant', 'bandstructure', 'chern', 'z2',
         'solid-state', 'tight-binding'
     ],
-    packages=[
-        'z2pack', 'z2pack.io', 'z2pack.fp', 'z2pack.volume', 'z2pack.surface',
-        'z2pack.line'
-    ]
+    packages=find_packages()
 )

z2pack/_run_utils.py

@@ -7,8 +7,6 @@
 
 from decorator import decorator
 
-from . import io
-
 __all__ = []
 
 
@@ -58,6 +56,7 @@ def _load_init_result(
 
     :returns: :class:`Result` instance.
     """
+    from . import io  # pylint: disable=import-outside-toplevel
 
     if init_result is not None:
         if load:

z2pack/surface/_run.py

@@ -11,11 +11,11 @@
 from . import SurfaceData, SurfaceResult
 from ._control import _create_surface_controls, SurfaceControlContainer
 
+from .. import io
 from .._run_utils import _load_init_result, _check_save_dir, _log_run
 from .._async_handler import AsyncHandler
 from .._logging_tools import TagAdapter, TagFilter, filter_manager
 from ..line import _run as _line_run
-from .. import io
 
 # tag which triggers filtering when called from the volume's run.
 _SURFACE_ONLY_LOGGER = TagAdapter(
@@ -154,6 +154,7 @@ def _run_surface_impl(
 
     The other parameters are the same as for :meth:`.run`.
     """
+
     # CONTROL SETUP
     ctrl_container = SurfaceControlContainer(controls)