Merge pull request #41 from ericpre/lazy_import

Lazy import

.github/workflows/tests.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        PYTHON_VERSION: [3.6, 3.7, 3.9]
+        PYTHON_VERSION: [3.7, 3.9]
         PIP_SELECTOR: ['[tests]']
         LABEL: [-RnM]
         include:

CHANGES.md

@@ -7,6 +7,7 @@
 * Add `is_binned` to axis GUI, make index of the navigation axis editable ([#39](https://github.com/hyperspy/hyperspy_gui_traitsui/pull/39)).
 * Fix loading GUI ([#38](https://github.com/hyperspy/hyperspy_gui_traitsui/pull/38)).
 * Improve rendering changelog on github and fix hyperlinks in `README.md` ([#42](https://github.com/hyperspy/hyperspy_gui_traitsui/pull/42)).
+* Speed up import time by importing submodules lazily ([#41](https://github.com/hyperspy/hyperspy_gui_traitsui/pull/41))
 
 ## v1.4.0 (2021-04-13)
 

hyperspy_gui_traitsui/__init__.py

@@ -16,24 +16,51 @@
 # You should have received a copy of the GNU General Public License
 # along with  HyperSpy.  If not, see <http://www.gnu.org/licenses/>.
 
-from hyperspy_gui_traitsui.version import __version__
 
+import importlib
 import logging
 
 import matplotlib
 from traits.etsconfig.api import ETSConfig
+
 from hyperspy.defaults_parser import preferences
 
 
-_logger = logging.getLogger(__name__)
+__all__ = [
+    'axes',
+    'messages',
+    'microscope_parameters',
+    'model',
+    'preferences',
+    'tools',
+    '__version__',
+    ]
 
 
-_logger.debug("Initial ETS toolkit set to {}".format(ETSConfig.toolkit))
+# mapping following the pattern: from value import key
+_import_mapping = {
+    '__version__':'.version',
+    }
+
+
+def __dir__():
+    return sorted(__all__)
+
+
+def __getattr__(name):
+    if name in __all__:
+        if name in _import_mapping.keys():
+            import_path = 'hyperspy_gui_traitsui' + _import_mapping.get(name)
+            return getattr(importlib.import_module(import_path), name)
+        else:
+            return importlib.import_module("." + name, 'hyperspy_gui_traitsui')
 
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
+
+
+_logger = logging.getLogger(__name__)
+_logger.debug("Initial ETS toolkit set to {}".format(ETSConfig.toolkit))
 
-WARN = (
-    not hasattr(preferences.GUIs, "warn_if_guis_are_missing") # hspy < v.1.3.1
-    or preferences.GUIs.warn_if_guis_are_missing)
 
 def set_ets_toolkit(toolkit):
     try:
@@ -51,6 +78,7 @@ def set_ets_toolkit(toolkit):
         _logger.debug("Setting ETS toolkit to %s failed" % toolkit)
         set_ets_toolkit("null")
 
+
 # Get the backend from matplotlib
 backend = matplotlib.get_backend()
 _logger.debug('Loading hyperspy.traitsui_gui')
@@ -63,21 +91,9 @@ def set_ets_toolkit(toolkit):
     # The toolkit has not been set and no supported toolkit is available, so
     # setting it to "null"
     set_ets_toolkit("null")
-    if WARN:
+    if preferences.GUIs.warn_if_guis_are_missing:
         _logger.warning(
             f"The {backend} matplotlib backend is not compatible with the "
             "traitsui GUI elements. For more information, read "
             "http://hyperspy.readthedocs.io/en/stable/user_guide/getting_started.html#possible-warnings-when-importing-hyperspy"
             ".")
-
-if ETSConfig.toolkit and ETSConfig.toolkit != "null":
-    import hyperspy.api_nogui # necessary to register the toolkeys
-    # Register the GUI elements
-    import hyperspy_gui_traitsui.axes
-    import hyperspy_gui_traitsui.model
-    import hyperspy_gui_traitsui.tools
-    import hyperspy_gui_traitsui.preferences
-    import hyperspy_gui_traitsui.microscope_parameters
-    import hyperspy_gui_traitsui.messages
-elif WARN:
-    _logger.warning("The traitsui GUI elements are not available.")

hyperspy_gui_traitsui/tests/test_import.py

@@ -1,18 +1,49 @@
-import unittest
+import pytest
+
 import hyperspy.api as hs
 import hyperspy.ui_registry
 
 
-class Test(unittest.TestCase):
-
-    def test_registry(self):
-        if "traitsui" in hyperspy.ui_registry.TOOLKIT_REGISTRY:
-            self.assertTrue("traitsui" in hyperspy.ui_registry.TOOLKIT_REGISTRY)
+def test_ui_registry():
+    if "traitsui" in hyperspy.ui_registry.TOOLKIT_REGISTRY:
+        assert "traitsui" in hyperspy.ui_registry.TOOLKIT_REGISTRY
+    else:
+        if "ipywidgets" in hyperspy.ui_registry.TOOLKIT_REGISTRY:
+            with pytest.raises(ValueError):
+                hs.preferences.gui(toolkit="traitsui")
         else:
-            if "ipywidgets" in hyperspy.ui_registry.TOOLKIT_REGISTRY:
-                with self.assertRaises(ValueError):
-                    hs.preferences.gui(toolkit="traitsui")
-            else:
-                # As ipywidgets is not installed it should raise an import error
-                with self.assertRaises(ImportError):
-                    hs.preferences.gui(toolkit="traitsui")
+            # As ipywidgets is not installed it should raise an import error
+            with pytest.raises(ImportError):
+                hs.preferences.gui(toolkit="traitsui")
+
+
+def test_import_version():
+    from hyperspy_gui_traitsui import __version__
+
+
+def test_import():
+    import hyperspy_gui_traitsui
+    for obj_name in hyperspy_gui_traitsui.__all__:
+        getattr(hyperspy_gui_traitsui, obj_name)
+
+
+def test_import_import_error():
+    import hyperspy_gui_traitsui
+    try:
+        hyperspy_gui_traitsui.inexisting_module
+    except AttributeError:
+        pass
+
+
+def test_dir():
+    import hyperspy_gui_traitsui
+    d = dir(hyperspy_gui_traitsui)
+    assert d == [
+        '__version__',
+        'axes',
+        'messages',
+        'microscope_parameters',
+        'model',
+        'preferences',
+        'tools',
+        ]

setup.py

@@ -53,7 +53,6 @@
     # See https://pypi.python.org/pypi?%3Aaction=list_classifiers
     classifiers=[
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
@@ -82,6 +81,7 @@
     # your project is installed. For an analysis of "install_requires" vs pip's
     # requirements files see:
     # https://packaging.python.org/en/latest/requirements.html
+    python_requires='~=3.7',
     install_requires=['hyperspy>=1.6.2', 'traitsui>=6.0'],
     extras_require={
         'tests': ['pytest'],