Reduce import time

Defer loading of VTK/PyVista modules to speed up import time

Author: sayerhs

caelus/config/jinja2wrappers.py

@@ -1,13 +1,12 @@
 # -*- coding: utf-8 -*-
+# pylint: disable=import-outside-toplevel
 
 """
 Utilities for working with Jinja2 templates
 """
 
 import os
 
-from jinja2 import Environment, FileSystemLoader
-
 from ..utils import osutils
 from ..version import version
 from . import config
@@ -41,6 +40,8 @@ def __init__(self, template_dirs=None):
         Args:
             template_dirs (list): Absolute path to template directories
         """
+        from jinja2 import Environment, FileSystemLoader
+
         tmpl1 = template_dirs or []
         tmpl2 = get_template_dirs()
         all_templates = tmpl1 + tmpl2

caelus/utils/vtk_helpers.py

@@ -1,33 +1,20 @@
 # -*- coding: utf-8 -*-
+# pylint: disable=import-outside-toplevel
 
 """\
 Wrappers for VTK/pyvista
 """
 
-try:
-    import vtk as _vtk
-
-    _has_vtk = True
-except ImportError:  # pragma: no cover
-    _has_vtk = False
-
-try:
-    import pyvista as _pyvista
-
-    _has_pyvista = True
-except ImportError:  # pragma: no cover
-    _has_pyvista = False
-
 
 def vtk():
     """Return the vtk module"""
-    if not _has_vtk:  # pragma: no cover
-        raise ModuleNotFoundError("Cannot locate vtk module")
+    import vtk as _vtk
+
     return _vtk
 
 
 def pyvista():
     """Return the pyvista module"""
-    if not _has_pyvista:  # pragma: no cover
-        raise ModuleNotFoundError("Cannot locate pyvista module")
-    return _pyvista
+    import pyvista as pv
+
+    return pv