2025-12-01

scripts/addons/blender_svn/wheels/__init__.py

@@ -0,0 +1,144 @@
+# SPDX-FileCopyrightText: 2025 Blender Studio Tools Authors
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+# NOTE: The original author of this file is Sybren Stüvel. This file is copied from the
+# Flamenco project: https://developer.blender.org/diffusion/F/browse/main/addon/flamenco/wheels/__init__.py
+
+"""External dependencies loader."""
+
+import contextlib
+from pathlib import Path
+import sys
+import logging
+from types import ModuleType
+from typing import Iterator
+
+_my_dir = Path(__file__).parent
+_log = logging.getLogger(__name__)
+
+
+def load_wheel(module_name: str, fname_prefix: str) -> ModuleType:
+    """Loads a wheel from 'fname_prefix*.whl', unless the named module can be imported.
+
+    This allows us to use system-installed packages before falling back to the shipped wheels.
+    This is useful for development, less so for deployment.
+    """
+
+    try:
+        module = __import__(module_name)
+    except ImportError as ex:
+        _log.debug("Unable to import %s directly, will try wheel: %s", module_name, ex)
+    else:
+        _log.debug(
+            "Was able to load %s from %s, no need to load wheel %s",
+            module_name,
+            module.__file__,
+            fname_prefix,
+        )
+        assert isinstance(module, ModuleType)
+        return module
+
+    wheel = _wheel_filename(fname_prefix)
+
+    # Load the module from the wheel file. Keep a backup of sys.path so that it
+    # can be restored later. This should ensure that future import statements
+    # cannot find this wheel file, increasing the separation of dependencies of
+    # this add-on from other add-ons.
+    with _sys_path_mod_backup(wheel):
+        try:
+            module = __import__(module_name)
+        except ImportError as ex:
+            raise ImportError(
+                "Unable to load %r from %s: %s" % (module_name, wheel, ex)
+            ) from None
+
+    _log.debug("Loaded %s from %s", module_name, module.__file__)
+    assert isinstance(module, ModuleType)
+    return module
+
+
+def load_wheel_global(module_name: str, fname_prefix: str) -> ModuleType:
+    """Loads a wheel from 'fname_prefix*.whl', unless the named module can be imported.
+
+    This allows us to use system-installed packages before falling back to the shipped wheels.
+    This is useful for development, less so for deployment.
+    """
+
+    try:
+        module = __import__(module_name)
+    except ImportError as ex:
+        _log.debug("Unable to import %s directly, will try wheel: %s", module_name, ex)
+    else:
+        _log.debug(
+            "Was able to load %s from %s, no need to load wheel %s",
+            module_name,
+            module.__file__,
+            fname_prefix,
+        )
+        return module
+
+    wheel = _wheel_filename(fname_prefix)
+
+    wheel_filepath = str(wheel)
+    if wheel_filepath not in sys.path:
+        sys.path.insert(0, wheel_filepath)
+
+    try:
+        module = __import__(module_name)
+    except ImportError as ex:
+        raise ImportError(
+            "Unable to load %r from %s: %s" % (module_name, wheel, ex)
+        ) from None
+
+    _log.debug("Globally loaded %s from %s", module_name, module.__file__)
+    return module
+
+
+@contextlib.contextmanager
+def _sys_path_mod_backup(wheel_file: Path) -> Iterator[None]:
+    old_syspath = sys.path[:]
+
+    try:
+        sys.path.insert(0, str(wheel_file))
+        yield
+    finally:
+        # Restore without assigning new instances. That way references held by
+        # other code will stay valid.
+
+        sys.path[:] = old_syspath
+
+
+def _wheel_filename(fname_prefix: str) -> Path:
+    path_pattern = "%s*.whl" % fname_prefix
+    wheels: list[Path] = list(_my_dir.glob(path_pattern))
+    if not wheels:
+        raise RuntimeError("Unable to find wheel at %r" % path_pattern)
+
+    # If there are multiple wheels that match, load the last-modified one.
+    # Alphabetical sorting isn't going to cut it since BAT 1.10 was released.
+    def modtime(filepath: Path) -> float:
+        return filepath.stat().st_mtime
+
+    wheels.sort(key=modtime)
+    return wheels[-1]
+
+
+def preload_dependencies() -> None:
+    """Pre-load the datetime module from a wheel so that the API can find it."""
+    module= load_wheel_global("six", "six")
+    _log.debug("Loaded wheel: %s", module.__name__)
+    module= load_wheel_global("dateutil", "python_dateutil")
+    _log.debug("Loaded wheel: %s", module.__name__)
+    module = load_wheel_global("send2trash", "Send2Trash")
+    _log.debug("Loaded wheel: %s", module.__name__)
+    module = load_wheel_global("xmltodict", "xmltodict")
+    _log.debug("Loaded wheel: %s", module.__name__)
+
+
+if __name__ == "__main__":
+    logging.basicConfig(level=logging.DEBUG)
+    wheel = _wheel_filename("python_dateutil")
+    print(f"Wheel: {wheel}")
+    module = load_wheel("dateutil", "python_dateutil")
+    print(f"module: {module}")