Add preference file support for Brian2CUDA (issue #281)

brian2cuda/__init__.py

@@ -2,13 +2,11 @@
 Package implementing the CUDA "standalone" `Device` and `CodeObject`.
 """
 import logging
+import os
 
-from . import cuda_prefs
+from . import binomial, cuda_prefs, timedarray
 from .codeobject import CUDAStandaloneCodeObject
 from .device import cuda_standalone_device
-from . import binomial
-from . import timedarray
-
 
 try:
     from ._version import __version__, __version_tuple__
@@ -36,6 +34,49 @@
 from .tests import run as test
 
 
+def _load_preference_files():
+    """
+    Load brian2cuda preference files from standard locations.
+
+    This function loads brian2cuda-specific preferences from user preference
+    files, avoiding the validation error that occurs when external package
+    preferences are added to the main preference file.
+
+    Files are loaded in the following order (later files override earlier ones):
+    1. ~/.brian2cuda_preferences (user-specific preferences)
+    2. ./brian2cuda_preferences (project-specific preferences)
+
+    Missing files are silently ignored. Invalid files generate warnings but
+    do not prevent the package from loading.
+    """
+    from brian2 import prefs
+
+    # Define preference file locations
+    user_prefs_file = os.path.join(
+        os.path.expanduser('~'), '.brian2cuda_preferences'
+    )
+    local_prefs_file = 'brian2cuda_preferences'
+
+    preference_files = [user_prefs_file, local_prefs_file]
+
+    for prefs_file in preference_files:
+        try:
+            prefs.read_preference_file(prefs_file)
+        except OSError:
+            # File doesn't exist, that's fine
+            pass
+        except Exception as e:
+            # Log a warning for other errors (invalid format, etc.)
+            logger = logging.getLogger('brian2cuda')
+            logger.warning(
+                f"Error reading preference file '{prefs_file}': {e}"
+            )
+
+
+# Load preference files when the package is imported
+_load_preference_files()
+
+
 def example_run(device_name="cuda_standalone", directory=None, **build_options):
     """
     Run a simple example simulation to test whether Brian2CUDA is correctly set up.
@@ -51,12 +92,13 @@ def example_run(device_name="cuda_standalone", directory=None, **build_options):
     build_options : dict, optional
         Additional options that will be forwarded to the ``device.build`` call,
     """
-    from brian2.devices.device import device, set_device
-    from brian2 import ms, NeuronGroup, run
-    import brian2cuda
     import numpy as np
     from numpy.testing import assert_allclose
 
+    import brian2cuda
+    from brian2 import NeuronGroup, ms, run
+    from brian2.devices.device import device, set_device
+
     set_device(device_name, build_on_run=False)
     N = 100
     tau = 10 * ms

brian2cuda/tests/test_gpu_detection.py

@@ -1,20 +1,20 @@
 import functools
-import os
 import logging
+import os
 from io import StringIO
 
 import pytest
 from numpy.testing import assert_equal
 
-from brian2 import prefs, ms, run, set_device, device
-from brian2.utils.logger import catch_logs as _catch_logs
+from brian2 import device, ms, prefs, run, set_device
 from brian2.core.preferences import PreferenceError
+from brian2.utils.logger import catch_logs as _catch_logs
 from brian2cuda.utils.gputools import (
-    reset_cuda_installation,
     get_cuda_installation,
-    restore_cuda_installation,
-    reset_gpu_selection,
     get_gpu_selection,
+    reset_cuda_installation,
+    reset_gpu_selection,
+    restore_cuda_installation,
     restore_gpu_selection,
 )
 
@@ -177,3 +177,113 @@ def test_no_gpu_detection_preference(reset_gpu_detection, use_default_prefs):
     prefs.devices.cuda_standalone.cuda_backend.gpu_id = 0
     prefs.devices.cuda_standalone.cuda_backend.compute_capability = device.minimal_compute_capability
     run(0*ms)
+
+
+### Preference file loading tests (Issue #281) ###
+@pytest.mark.codegen_independent
+def test_missing_files_no_error(use_default_prefs):
+    """
+    Test that missing preference files don't cause errors.
+
+    Regression test for issue #281:
+    https://github.com/brian-team/brian2cuda/issues/281
+    """
+    import importlib
+    import tempfile
+
+    import brian2cuda
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        original_home = os.environ.get('HOME')
+        original_cwd = os.getcwd()
+
+        try:
+            # Use empty directory (no preference files)
+            os.environ['HOME'] = tmpdir
+            os.chdir(tmpdir)
+
+            # Should reload without error
+            importlib.reload(brian2cuda)
+
+            # Check it doesn't crash - preference should have a value
+            assert prefs['devices.cuda_standalone.SM_multiplier'] is not None
+        finally:
+            if original_home:
+                os.environ['HOME'] = original_home
+            os.chdir(original_cwd)
+
+
+@pytest.mark.codegen_independent
+def test_load_user_preference_file(tmp_path, use_default_prefs):
+    """
+    Test that user preference file (~/.brian2cuda_preferences) loads.
+
+    Regression test for issue #281:
+    https://github.com/brian-team/brian2cuda/issues/281
+    """
+    import importlib
+
+    import brian2cuda
+
+    # Create preference file in user's home directory
+    prefs_file = tmp_path / ".brian2cuda_preferences"
+    prefs_file.write_text("""
+[devices.cuda_standalone]
+SM_multiplier = 3
+launch_bounds = True
+""")
+
+    original_home = os.environ.get('HOME')
+    os.environ['HOME'] = str(tmp_path)
+
+    try:
+        # Reload to trigger preference loading
+        importlib.reload(brian2cuda)
+
+        # Check preferences were loaded
+        assert prefs['devices.cuda_standalone.SM_multiplier'] == 3
+        assert prefs['devices.cuda_standalone.launch_bounds'] is True
+    finally:
+        if original_home:
+            os.environ['HOME'] = original_home
+
+
+@pytest.mark.codegen_independent
+def test_local_overrides_user(tmp_path, monkeypatch, use_default_prefs):
+    """
+    Test that local preference file overrides user file.
+
+    Regression test for issue #281:
+    https://github.com/brian-team/brian2cuda/issues/281
+    """
+    import importlib
+
+    import brian2cuda
+
+    # Create user file
+    user_file = tmp_path / ".brian2cuda_preferences"
+    user_file.write_text("""
+[devices.cuda_standalone]
+SM_multiplier = 2
+""")
+
+    # Create local file with different value
+    local_file = tmp_path / "brian2cuda_preferences"
+    local_file.write_text("""
+[devices.cuda_standalone]
+SM_multiplier = 5
+""")
+
+    original_home = os.environ.get('HOME')
+    os.environ['HOME'] = str(tmp_path)
+    monkeypatch.chdir(tmp_path)
+
+    try:
+        # Reload to trigger preference loading
+        importlib.reload(brian2cuda)
+
+        # Local should override user
+        assert prefs['devices.cuda_standalone.SM_multiplier'] == 5
+    finally:
+        if original_home:
+            os.environ['HOME'] = original_home