Reimplement lazy importing using importlib

actions/generate_recipe.py

@@ -37,7 +37,6 @@
 
 RUN_DEPS = {
     "gsl",
-    "lazy_import",
     "libnetcdf",
     "openmm",
     "pandas",

doc/source/acknowledgements.rst

@@ -475,12 +475,6 @@ The header documentation reads;
      imshow does not plot axis yet.
      make a correct documentation
 
-lazy_import
------------
-
-:mod:`sire` uses `lazy_import <https://github.com/mnmelo/lazy_import>`__ to
-lazy load the modules. This is licensed under the GPLv3.
-
 rich
 ----
 

doc/source/changelog.rst

@@ -17,6 +17,11 @@ organisation on `GitHub <https://github.com/openbiosim/sire>`__.
 
 * Please add an item to this CHANGELOG for any new features or bug fixes when creating a PR.
 
+* Replaced the third-party ``lazy_import`` dependency (GPLv3) with a minimal, standard-library-only
+  ``importlib``-based implementation in ``sire.utils._lazy_import``. This also fixes a bug where
+  lazily-loaded modules could end up with two distinct class objects for the same module path
+  (e.g. via unpickling in a separate process), causing spurious ``isinstance()`` failures.
+
 * Fixed ``sire.restraints.boresch()`` setting a dynamic ``_use_pbc`` Python attribute on
   the returned ``BoreschRestraints`` instead of calling ``set_uses_pbc()``, which broke
   pickling (e.g. for ``multiprocessing``/``ProcessPoolExecutor``) and meant the flag did

pixi.toml

@@ -12,7 +12,6 @@ cmake = ">=3.30.0"
 git = "*"
 pybind11 = "*"
 gsl = "*"
-lazy_import = "*"
 libboost-devel = "*"
 libboost-python-devel = "*"
 libcblas = "*"

src/sire/CMakeLists.txt

@@ -115,7 +115,7 @@ add_subdirectory (vol)
 
 install( FILES __init__.py _load.py _match.py
                _parallel.py _pythonize.py
-               _measure.py _colname.py
+               _measure.py _colname.py _lazy_import.py
          DESTINATION ${SIRE_PYTHON}/sire
        )
 

src/sire/__init__.py

@@ -803,56 +803,77 @@ def _convert(id):
 __repository__ = config.sire_repository_url
 __revisionid__ = config.sire_repository_version[0:7]
 
-_can_lazy_import = False
-
-if "SIRE_NO_LAZY_IMPORT" not in _os.environ:
-    try:
-        import lazy_import as _lazy_import
-        import logging as _logging
-
-        _logger = _logging.getLogger("lazy_import")
-        _logger.setLevel(_logging.ERROR)
-
-        # Previously needed to filter to remove excessive warnings
-        # from 'frozen importlib' when lazy loading.
-        # import warnings
-        # warnings.filterwarnings("ignore")
-
-        _can_lazy_import = True
-
-    except Exception as e:
-        print("Lazy import disabled")
-        print(e)
-        _can_lazy_import = False
+from ._lazy_import import lazy_module as _lazy_module
 
+_can_lazy_import = "SIRE_NO_LAZY_IMPORT" not in _os.environ
 
 # Lazy import the modules for speed, and also to prevent pythonizing them
-# if the users wants to run in legacy mode
+# if the users wants to run in legacy mode.
+#
+# _lazy_module() doesn't execute anything regardless of call order - it
+# just registers a stub - so the order here is cosmetic; kept alphabetical.
+# See the eager fallback below for the one case where order does matter.
 if _can_lazy_import:
-    analysis = _lazy_import.lazy_module("sire.analysis")
-    base = _lazy_import.lazy_module("sire.base")
-    cas = _lazy_import.lazy_module("sire.cas")
-    convert = _lazy_import.lazy_module("sire.convert")
-    cluster = _lazy_import.lazy_module("sire.cluster")
-    error = _lazy_import.lazy_module("sire.error")
-    ff = _lazy_import.lazy_module("sire.ff")
-    id = _lazy_import.lazy_module("sire.id")
-    io = _lazy_import.lazy_module("sire.io")
-    maths = _lazy_import.lazy_module("sire.maths")
-    mm = _lazy_import.lazy_module("sire.mm")
-    mol = _lazy_import.lazy_module("sire.mol")
-    morph = _lazy_import.lazy_module("sire.morph")
-    move = _lazy_import.lazy_module("sire.move")
-    options = _lazy_import.lazy_module("sire.options")
-    qm = _lazy_import.lazy_module("sire.qm")
-    qt = _lazy_import.lazy_module("sire.qt")
-    restraints = _lazy_import.lazy_module("sire.restraints")
-    search = _lazy_import.lazy_module("sire.search")
-    squire = _lazy_import.lazy_module("sire.squire")
-    stream = _lazy_import.lazy_module("sire.stream")
-    units = _lazy_import.lazy_module("sire.units")
-    utils = _lazy_import.lazy_module("sire.utils")
-    vol = _lazy_import.lazy_module("sire.vol")
+    analysis = _lazy_module("sire.analysis")
+    base = _lazy_module("sire.base")
+    cas = _lazy_module("sire.cas")
+    cluster = _lazy_module("sire.cluster")
+    convert = _lazy_module("sire.convert")
+    error = _lazy_module("sire.error")
+    ff = _lazy_module("sire.ff")
+    id = _lazy_module("sire.id")
+    io = _lazy_module("sire.io")
+    maths = _lazy_module("sire.maths")
+    mm = _lazy_module("sire.mm")
+    mol = _lazy_module("sire.mol")
+    morph = _lazy_module("sire.morph")
+    move = _lazy_module("sire.move")
+    options = _lazy_module("sire.options")
+    qm = _lazy_module("sire.qm")
+    qt = _lazy_module("sire.qt")
+    restraints = _lazy_module("sire.restraints")
+    search = _lazy_module("sire.search")
+    squire = _lazy_module("sire.squire")
+    stream = _lazy_module("sire.stream")
+    system = _lazy_module("sire.system")
+    units = _lazy_module("sire.units")
+    utils = _lazy_module("sire.utils")
+    vol = _lazy_module("sire.vol")
+else:
+    # SIRE_NO_LAZY_IMPORT is set - import everything eagerly instead, so
+    # these are still bound as expected. Ordered to match
+    # _pythonize.py's _load_new_api_modules() (base first, then move, io,
+    # system, squire, mm, convert, ff, mol, analysis, cas, cluster, error,
+    # id, maths, morph, restraints, qt, stream, units, vol), with the
+    # modules pythonize doesn't force-load (options, qm, search, utils)
+    # appended at the end.
+    from . import (
+        base,
+        move,
+        io,
+        system,
+        squire,
+        mm,
+        convert,
+        ff,
+        mol,
+        analysis,
+        cas,
+        cluster,
+        error,
+        id,
+        maths,
+        morph,
+        restraints,
+        qt,
+        stream,
+        units,
+        vol,
+        options,
+        qm,
+        search,
+        utils,
+    )
 
 
 def _version_string():